I think we can establish Kuz is erratic and unpredictable, judging by his behavior on the Sharty, both leading upto and during his time owning it.
But there's really nothing connecting Kuz with anyone IRL yet - that's where i feel like it's a bit of a leap to assume he's related to Mikhail Kuznets. I like the theory, since his IPs are from TN, but nothing really proves it yet.
I don't believe he's actually Russian though, at least by nationality, though quite possible he is an American of Russian or Eastern European descent.
Age, i'm a bit more uncertain. If we believe the Discord dump, he's around 19, otherwise i'd imagine he could be anywhere between that and his claimed age of 35.