The people who write fic are usually the sorts of people who are voracious media consumers. I've seen people talking about going out and buying a whole series of something just to have recent viewing/reading of canon for a Yuletide story. They're the sorts of folks that will spread news about a new release (for good or ill, but all publicity is good publicity, right? Well, mostly.) I think authors who "disallow" fic are shooting themselves in the foot. I tend to avoid authors that do that just because I don't want to go looking and be disappointed. (I find that they sometimes conflate ficcers with pirates too, which is very offputting.) It's all annecdata, but I'd say yes, or at least it doesn't hurt.