Ah, Dark Dungeons, how do I love thee!
Ironically, when the whole "D&D is satanic" thing was big in the 80's sales went up! When it was revelaed that D&D turns kids into nerds and not satanists the whole thing blew over. We're such a small market that book burnings can only help our industry.
I think Jack Chick is a fascinating person. His claims about his own life are truly remarkable. He's quite old and stopped doing his own artwork in the 60s (IIRC). He had his personal revalation sometime in the 50s after he served in the army during WW2. What's really wild is that he says he worked on some of the original RPGs before he started drawing his tracts. Gary Gygax would have been around 10 years old at the time if this were true.
In any case, he remains the world's most published author. Given that a google search reveals more parody/debunking/"Jack Chick hates D&D" sites than actual Jack Chick fan sites, I'm not terribly concerned about his influence.