Good news and bad news: If you are involved with an alcoholic, then your acquaintances here will last a lifetime. This is a lifetime illness. Having said that, we are happy you have found your way to this forum and are pleased to make your acquaintance.
I'm sorry you are going through this. I know how hard it is to watch someone you love do this to themselves.
I'm not sure there is an answer to your question. My AH was also drinking full bottles of vodka every day for a very long time. I honestly did not believe he would live. I had given up all hope of ever seeing him come through it. But he finally did. I can't explain why his body appears to have suffered no ill effect as a result of his drinking (for 30+ years). It seemed to go beyond any medical explanation. How he came to find his way back has been the most spiritual awakening of my life. I can only describe it as a divine intervention. What I believe is this: The life and breath of all mankind is in the hands of God.
If your AH is drinking as much as you say, then he can't be functioning very well anymore. Try to resist the urge to "do" for him. He could be close to his bottom, IF you allow him to hit it.