If the relationship started off based on sex..it would have a hard time surviving. If you have things in common, etc on top of the sex..than maybe.
I've seen a few sex buddy relationships turn into real ones, but not without their problems. It really depends what you agreed on from the beginning. And wether or not you are both open to having a relationship. Sometimes people get into sex with benefits situations because they arent ready for a BF or GF. If thats the case..I dont see why having sex with you a few times would change his mind.
From my experience..usually the guy will say "I'm not looking for a relationship right now" and I think you should take him for his word.
Not sure if this helps..but if you are starting to have feelings..maybe tell him. Expect him to either have feelings back, or run for the hills. Be prepared for either one of those senarios.