I'd say that Spike liking pr0n is fanon, but fanon based on a firm grasp of reality. ;-) However, it's canon that he visited a strip club in AtS S5. Is it the same thing? Pretty much.

Weirdly, Spike doesn't actually do the male gaze thing with women much on BtVS. Only Buffy and Harmony (and Anya that one time) get "the look". I often write him bird-dogging, though. Even in front of Buffy...though generally as a smokescreen for the benefit of others in S6.