I've heard it said both ways on the news today, but I'm leaning towards R-Evil.
r/evil
It is REE-vil.
Neither. It’s REvil.
Not sure why you're being downvoted, you're right! It's REvil, from "Ransomware Evil", bunch of different sources confirming this, too many to link. But Wikipedia keeps a good list: https://en.wikipedia.org/wiki/REvil
GGP is asking about pronunciation, not spelling. Saying "it's REvil" does not help clarify pronunciation at all.
It's tounge-in-cheek but try out "revil" (that's like the e in "reverend", not in "evil")
Ha, so I was right in my adjacent comment. BTW, that's how I've also instinctively pronounced REvil in my head, too.
Perhaps @lordnacho couldn't decide between ARE-Evil ('A@r-'i:v@L) and REEvil (r'i:v@L), so @3np suggested REvil (r'Ev'Il). J/k, I'm just showing off `eSpeak -x`'s output, which as a non-native English speaker I've found quite valuable on occasion.