Does he actually want to quit but is highly addicted? Or is he still enjoying this habit?
Odd question I appreciate but it makes a huge difference as to how you treat it.
If he does actually want to quit but is struggling then send him to a hypnotherapist:
https://www.melaniebearne.com/
If he is enjoying this habit and just wants to continue then I agree with ronangel above - get out the life insurance plans and make it very clear what he is doing.
Good luck.