Stage IV is very serious. He may cure his Hep C, but the cirrhosis will last forever. Not only that, but it predisposes him to bleeding, ruptured vessels in the stomach and esophagus, life-threatening infections in the belly, and hepatocellular carcinoma (cancer). If he can lead a good, clean life for a year, there is a good chance he can get a liver transplant. Please be sure he has a good hepatologist (a specially trained gastroenterologist). He needs to have a small camera passed into his stomach to look for vessels that can rupture, and he needs a scan to make sure there isn't a mass in his liver.
I just diagnosed someone with this, and he wound up having cancer at diagnosis because he didn't see his doc often enough early on.
I don't want to scare you, but be sure he gets good care. Be there for him, because he is scared whether he shows it or not.
Best of luck.