It can be pronounced either way - I've always pronounced it -VI- talking about the spine / neck, and -VAI- talking about womb bits, but I'm not aware of any rules about it, arbitrary or otherwise.
Than being said - he's a massive cunt. Pronounced K-U-N-ihopehisfacerotsofftheutterballbag-T.
Southend News Network wins big time:
https://www.youtube.com/watch?time_continue=175&v=FncNrlxxMUk