Request to change rooms because of the smoke smell. Also, you requested a non-smoking roommate and you were paired with a roommate who smokes. Probably because he did not list that he smoked, but that does not matter now.
I don’t think you’ll have to convince anyone that he smoked in the room. Just complain that smokers smell like smoke and that is why you requested a non-smoking roommate in the first place.
Good luck.