The best theoretical model for pricing vix futures and options is a variance gamma model.
However in practice that class of models is difficult to get robust results...
In practice, most floor traders in vix products base their hedging off of the SPX option chain. Vix is calculated from those options, in the first place, so this approach makes intuitive sense. Isolating the variance component of those the SPX options is straightforward using several approaches, and does not require much sophisticated numerical work.