My boyfriend has to go back to prison. He violated parole, five year sentence, So how much of that time well he have to do?

Depends on the original sentence and how the judge or ALJ feels. Might be 5 years. Misdemeanor or felony?

Also if his violation was an actual new crime.. where more time will end up added.

When he is revoked, he will have a hearing, and the judge will tell him, how long, he can serve up to the entire 5years. Also, if there are new charges, those can be added on