He's an advisor to Omise Go and some other weirdly named ICO (Kyber?), but that's it. People have just been using his name without permission.

At least that's what Vitalik said on Twitter. With this, I don't mean to imply that TenX is a scam, I'm simply stating the facts, namely that Vitalik has not officially endorsed the project, something he has done with Omise Go.