The movie isn't considered canon because Joss decanonized it, since he didn't like what they did with his script. But there's a comic called "The Origin" which is an adaptation of Joss's original script, and Joss said it was "pretty much canon".

Pike seems to me like a mix of Spike and Xander. He was also brought back in a couple of other Dark Horse comics released during the show, which have never been recognized as canon but haven't been contradicted by canon either, so I guess anyone can decide how to treat them.

http://buffy.wikia.com/wiki/Oliver_Pike