Perhaps this is a controversial stance but I think if praying is part of your gambling process you probably shouldn’t be gambling maybe.
It depends on someone's belief. If in his/her belief that praying doesn't deserve to include in gambling, it shouldn't be a part of gambling. While if in his/her belief that praying is something usual in the game like gambling, so just go to pray in gambling. Actually, this something shouldn't be debated because basically the choice of an individual. I don't know why many people debate it here although they know it is the right of the individual.
someone's belief in what they believe is their basic right and we certainly can't force it on other people, what they do we don't necessarily think is right, as well as what we do may not be in line with their beliefs, but I really believe all Religions in the world teach goodness to their people, Every gambling player certainly wants victory and not defeat and usually Prayers and spell are always spoken from the mouth of almost all gambling players and they hope to win and in my opinion every intention and hope of winning that is in the heart is a prayer, and usually gamblers will hope that they get lucky in the game.