At the very least, he's a surrogate father figure to be certain, but from the stories he tells, and the UST between him and Lola's mom, it really does seem that Garrison at least seems to be acting on the assumption or strong suspicion of Lola's parentage.
Nobody else seems to take notice of her except Guy, and she is an Angel Of Death. Given that the theme of the whole movie is that Everybody Dies and that all good things come to an end, and that it's narrated by Guy...
However ...
This conclusion is merely the tip of the iceberg.
See, Garrison Keillor? He played the Sburb session that created our universe. (He was the Bard of Rage for his session, but as he was naturally much nicer than Gamzee, instead of going all Murder Mode, he merely used his soothing voice to invite the destruction of rage in others. ) Upon creating our universe and finding his place in it, he decided to tell his tale as part of a radio series, to provide hints to the players to come. Among these hints was a tip for Derse dreamers, like Garrison was, about Jack Noir, since Garrison met him several times.