Any speculation about the possible consequences of this probation violation would be meaningless without a complete review of the file, and talking with the District Attorney, the judge and the probation officer.
This young man needs an attorney; if he can't afford to hire an attorney himself, the judge will appoint the public defender to represent him. The fact that he has already had one violation, and served two months, makes it more likely that he will actually be sent to prison for the balance of the two year term.
Please understand that this is a general discussion of legal principles by a California lawyer and does not create an attorney/client relationship. It's impossible to give detailed, accurate advice based on a few sentences on a website (and you shouldn't provide too much specific information about your legal matter on a public forum like Avvo, anyway). You should always seek advice from an attorney licensed in your jurisdiction who can give you an informed opinion after reviewing all of the relevant information.
This person should have an attorney. They wil have more knowledge of options available. This can't be ansewered by anyone else without a complete review of the files and knowledge of the courts.
I agree with the first two answers, however, I would also point out that in light of his past behavior and all the various times he's been in jail, its more likely that he'll do time for the Violation of Probation, then not.
As the other two answers said, its best that he gets a competent experienced lawyer who can point out his good points, if any, to the Court, in order to mitigate his exposure to jail. Otherwise, there is no telling how much more time he will do without further information.