I'm not sure why you're "uncertain" about whether he's drinking, Didn't he just say he's been drinking a case of beer a day? And when you asked directly whether he's drinking "now" and he said, "no" and changed the subject.
Well, duh. He didn't have a drink in his hand at that moment, so he figures he can say "no". "Managing," for an alcoholic, means nothing horrible has happened recently even though s/he continues to drink. I think there is ZERO to be "uncertain" about. He's still drinking. Maybe he changed up the pattern a bit, or switched drinks, or cut down a bit in an effort to "control" it. Those tactics NEVER work.
All he is doing is trying to hold onto the status quo. If you want things to change YOU have to change them. And since you can't change HIM...