My friend used to drink a lot, like get pass out drunk everyday and night for years straight and he quit drinking. will he be okay now?

Better than he would: have been if he kept on drinking. How ok he will be depends on how well he works a sobriety program, and whether he has already done significant damage to his body. If he is close to your age, and hasn't been drinking heavy that long, the odds are good that whatever damage has been done will heal, but there is no way to say that without knowing your friend's medical issues.