That theory was debunked a while ago. The number of comic readers is miniscule compared to the number of movie goers. The analysis I saw concluded that Fox could take out a full-page ad in every issue of Fantastic Four that said "We hate you morons, don't see our movie!" and if every single FF reader obeyed those ads, they'd lose a total of $500K in box office receipts. McFarlane's Spider-Man #1 sold 2.5 million copies, one of the highest print runs of all time. If they all sold to distinct individuals (they didn't), and every one of them went to see a 3D, prime time feature (~ $15), that'd total $37.5 million dollars. Guardians of the Galaxy made that in one single day.
The idea that canceling a book could hurt a movie, or that Marvel would do such a thing to that end, makes no sense whatsoever.