OP, in case this helps—he can take FMLA leave (if he has worked there more than a year and if employer has at least 50 employees in a 75 mile radius of him) of up to 12 weeks to deal with this, OR he can request an unpaid leave of absence of a definite period under the ADA as a reasonable accommodation. But once he has violated work policy due to the addiction, they can fire him— addiction is itself protected but the stuff it makes him do is not. So it’s in his interest to get help before they catch him screwing up.
If he’s in DC, NY or California, he likely has additional rights yo get partial pay during a medical leave of absence (search paid family leave for whichever state).

Prayers, OP. If he is on meth, you need to be very careful with him. Tough love tempered with mercy and compassion, and adjust your expectations, because meth is the gateway drug to the grave. If he's on meth, he is also around other hard drugs, and fentanyl is what you need to be most concerned about, because it only takes a tiny amount to kill a grown man. Most hard drugs are "dirty" these days, meaning that they are cut with other substances.