You asked me about your friend — whether there's any reaching him, whether the right words at the right moment might finally take hold. I want to be honest with you, because you deserve that more than you deserve comfort.
There are people who are ready to be changed, and people who think they are. The difference isn't visible from the outside, and it isn't even always visible from the inside. Your friend believes he wants to live differently. I don't doubt that he believes it. But belief and readiness aren't the same thing, and what he's been doing to himself for years has made the soil poor.
A vine that's been neglected long enough won't take a graft. Not because the vine is evil, but because it no longer has what's needed to nourish something new. You can try — sometimes you cut back hard and try again lower down, closer to the root, where there might still be strength. But the vine has to have something left to give.
Men love and hate their vices at the same time.
This is the thing to watch for. He's not on speaking terms with his habits right now — there's been a quarrel, some discomfort, a moment of genuine disgust. That's real. But disgust and departure are different. Wait and see whether the estrangement holds, or whether they reconcile quietly when conditions improve and the discomfort fades.
You can't want change on someone else's behalf hard enough to make it happen in them. What you can do is be there, without pressure, for the moment when the wanting becomes real. That moment may come. Keep the door open. But don't grieve yet over someone who is still deciding.
With love for you, and patience for him,