it's purple belt level at worst from what I'm seeing.
there are different standards to belt levels based on gyms and even within gyms (some trainers will give an easier path to hobbyists than to competitors).
John Danaher has guys at blue belt trying to make world BJJ champion runs and then there are black belts who look like fish on the ground in MMA.
also what the expectations are of attaining a black belt differ from place to place.
in some traditions, you need to be well-versed in the Gi (most UFC fighters don't even bother training in the Gi).
in some traditions, you need to successfully apply BJJ outside of sports grappling context (in real fighting/MMA).
in some traditions, you just do no Gi training (10th planet stuff).
in some traditions, you just show up to training for at least 5-7 years and you're getting your black belt.
what I will say is that your average UFC fighter will beat most guys in his equivalent belt level in most gyms they visit purely by athleticism.
a purple belt in BJJ like me who works in IT and does BJJ as a hobby will get destroyed by any purple in the UFC. It wouldn't even be competitive.