He's not going to be able to adjust his status because he has no status. If he leaves the U.S. he will be subject to a lifetime bar due to his illegal reentry after deportation. He has a small chance of getting a waiver of his ineligibility (although not while he remains in the U.S. - he has to apply from outside of the U.S.); you can discuss the situation in detail with an immigration lawyer to have that chance assessed.