A domestic violence charge will definitely be a candidate for reason to revoke. I am sure that he will be violated if the case goes beyond the initial hearing date. However, it may be enough to violate simply for the subsequent arrest or just contact with law enforcement. Violations for probation don't always need a conviction in order for the officer to violate. Whether or not he violates simply because of the new charge depends on the probation department's rules.

He can be held for the length of his sentence depending on whether or not he has his probation revoked. Too little information to give you an accurate answer on that.