There is a saying in the addiction community: “If nothing changes, then nothing changes.” He has to want to change, first.
You can’t make him. But God does weird things, so get him involved.
Find a good church that will pray for him. Then find help within that church family to set up an intervention; meaning, a clear presentation of the Gospel of Jesus Christ, the offering of a new path that leads to a life with purpose and peace, vice the eternal destruction he is facing.
Having done that, it’s placed in God’s hands.
That’s the best advice, I think. Have to plead in earnest with God to intervene!
This is the strongest advice possible.