Colbert Bump: A number of games have experienced a surge in popularity after Chugga LPed them.
Ōkami in particular got a lot more sales after he started playing it. Coincidentally, Ōkamiden was released near the end of his series, and likely gained popularity thanks to the first game's new fanbase.
Zig-zagged; he regrets creating the "Steve" meme and wants to move on from it, but on some occasions he still indulges the fans with shout outs to him:
In The Runaway Guys's New Super Mario Bros. Wii LP, the gang decided to name everything that killed the characters. One of the members suggested Steve and Emile immediately rejected it.
Emile: NO, no, nothing is named Steve!
He's made a bonus video of Pikmin's challenge mode and gone all the way to 60% of completing the main game in Pikmin 2 at the time of writing without going much further than calling leaves stupid, though if you listen closely, you can hear him stopping himself.
In another episode of Pikmin 2, he actively tries to put the Steve business to rest by saying the odds of any Pikmin being the same from the first game are near impossible.
The Stinger of one Pikmin 2 episode features one of Pikmin 2's intro scenes, with tons of red leaf Pikmin piling onto the Nintendo logo. Chugga proceeds to say:
In Episode 6 of Majora's Mask, he finally caves in...BIG TIME!
OKAY FINE! STEVE! THERE YOU GO! HAPPY?! I SAID IT! IT STOPPED BEING FUNNY AFTER THE PIKMIN 1 LP!
Despite all of the above he has referenced him in a more positive light in other videos:
He finally makes an offhand reference to Steve in Episode 40:
Emile: Ironically he was not a red leaf though so he was not an idiot like, you know, typically though, but then again, red leafs can be heroes when they really try in very specific situations... as many as you happily recall...
And then continues it again, in a later episode, twice. Once was when a Bulbmin continued attacking the Man-At-Legs despite the whistle (and staying alive), Chugga commented he should turn the Bulbmin into a red Pikmin. The other time was when he said that day was the birthday of a hero of some kind. The day he updated (or at least the day he recorded) was the same day his first episode of Pikmin 1 came out, and when Steve was first plucked.
And in the finale of Pikmin 2, Chugga lets a red leaf carry back Louie after the final battle. He even says "Go ahead and say hi!"
In The Runaway Guys Subspace Emissary videos, ProtonJon takes great pleasure in bringing up Steve when Olimar is introduced, even forcing Chugga to play as him. Chugga is NOT happy about this. To make it even more ridiculous, the gag begins with a cutscene where Captain Falcon accidentally kills all of Olimar's Pikmin except...
Development Hell: His video showing the library and backstory to Super Luigi Galaxy. It was supposed to be posted within a few days of the end of the regular LP — instead, due to illness and starting a new LP, he didn't even start working on it until nearly 2 months later.
He originally planned to show off some items in his Mother LP, but he forgot to do so. He eventually released them as Part 37 of his LP... which came out on his 3-year anniversary, 2 years and 8 months after he finished the Mother LP (which was his second LP).
Flip Flop of God: During his Super Mario Sunshine LP, he stated that he did not intend to LP Super Mario 64 or Super Mario Galaxy, due to those games being, in Emile's opinion, over-LPed (and in the case of 64, overrated as well). He's kept his word regarding SM64, but less than a year later, he posted the first installment of his Galaxy LP. True, it was technically SuperLuigiGalaxy, but... same game, so the point still stands.
And NOW he's doing an LP of Mario 64... even if it is the DS remake, the point still stands.
While he never directly says this about Flannery, on the video of his Emerald LP where he says she Needs More Love, one of the comments said he loves her because she's a redhead.
One of Us: He wound up outing himself as a tropernote Not to be confused with a trooper. EVER. in his videos of The Runaway Guys, mainly, his repeated usage of saying "Press A to not die" (and on the guys' SSBB LP, "Press Start to not die").
Emile: "Tim has finally gotten the concept of pressing A to not die, but now there's a twist, it's 'Press Start to not die'! Can you master the art of 'Press Start to not die', Tim?"
In Ōkamiden, he even mentions reading his own pages and having major respect for the people who edit them so fast.
Chugga: I don't know who runs my TV Tropes page, but I gotta say this: I have undying respect for whoever you person or persons are because you keep that thing updated like nuts. Especially the Funny page. My god, it's nuts.
Schedule Slip: In July 2013, his LP of Super Mario 64 DS took an unexpected ten-day hiatus after an illness ruined his voice AND a lightning strike knocked out his Internet connection.
Xenoblade Chronicles took a three-week hiatus due to real-life shenanigans, including travel and an unexpected illness. And during PAX Prime 2014, his illness has returned causing another delay.
What Could Have Been: In an interview with LPCatchphrases, he mentions that some of his early plans for Let's Plays that never materialised included Yoshi's Island (he tried a few videos and wasn't happy with the result) and Eternal Sonata, which would have been the first LP of a game not available on a Nintendo console.
He also planned to do Luigi's Mansion and Pikmin earlier than he did, but was put off by the (then) Youtube time limit.
Kirby's Epic Yarn was originally supposed to be a collaborative LP on The Runaway Guys, but was rejected due to the 2-player mode not working very well, specially due to the fact that they could not screw each other over in gameplay. So Chugga decided to do it alone.
He still showed off two-player mode with ProtonJon at the end though.