Look at this user. He is answering only his own questions. My question is: Does this increase reputation?
Does it increases reputation ?
You do not get the 15 points (or the +2) for accepting your own answer on a self-answered question. However, votes still count as usual (that is +10 for an upvote, -2 for a downvote).
Other than that, there is nothing about self-answering that inherently increases reputation beyond the normal rules.