I dont really think so ... I think in gambling everything is about your luck and your lucky day, a lot of times i had a good feeling for something, im going all in and losing everything. I think being super confident and feeling good before placing a bet in gambling is the worst thing, at the end you lose money 
But i think that positive thinking is not only important but in every field of life we need to think as positive, which give us strength and hope and so it can increase the chances of our winning. I always think positive when play gambling and it always increase my confident level and through this way i increase the rate of taking a right decision in right time.