Stalemate is a situation in chess where the player whose turn it is to move is not in check and has no legal move. Stalemate results in a draw. During the endgame, stalemate is a resource that can enable the player with the inferior position to draw the game rather than lose. In more complex positions, stalemate is much rarer, usually taking the form of a swindle that succeeds only if the superior side is inattentive.Stalemate is also a common theme in endgame studies and other chess problems.

The outcome of a stalemate was standardized as a draw in the 19th century. Before this standardization, its treatment varied widely, including being deemed a win for the stalemating player, a half-win for that player, or a loss for that player; not being permitted; and resulting in the stalemated player missing a turn. Stalemate rules vary in other games of the chess family.
If I have more pieces at the time of stalemate, have I won?
No. 
Stalemate is a drawn position. It doesn't matter who has captured more pieces or is in a winning position