No way, no user account will keep winning. They will go bankrupt if there is an account that always wins the games. 

If the casino wants to do it, I think it is possible. But the casinos are probably fair, they must try to keep the trust of all users. If there is something strange on the casinos, the users will leave the casinos. So, I still assume the casino sites will try to be fair. They won't control the win or lose of each user.

How can a new account to have a higher chance? The chance to win doesn't depend on how long you stay in the casino site.