Someone I know got arrested for violation of probation. can he get out of jail early if the restitution was pay in full?

I would bring this up with his probation officer and see if he or she can help.

This depends upon what the Judge sentences the person to. If he has already been sentenced then the judge could reconsider the charge if it is within the time period required for a motion of reconsideration., otherwise this person has to do the jail time.