Nothing has changed since this thread was posted.
I have been waiting for 43 days since submitting my withdrawal request. Nitrobetting should receive a serious warning on this forum as a potential exit scam, because from what I can see, the number of similar cases is increasing.
They already have some negative tags from members and a flag from someone, but it is inactive. Apart from that, and members giving warning to people who would ask about nitrobetting, there isn't really much that can be done.
Website probably goes offline and disappears by the end of the year.
I was expecting them to go offline last year or earlier this year when complaints like yours and OP started popping up.