When will Juvederm Volite be available in the US?

It is impossible to say when, or if , Juvederm Volite will be available in US. It all depends on FDA which grants approvals that are not always based on the safety or effectiveness.
Volite is a "hydrating" filler with similar indications to Juvederm Hydrate or Stylage HydroMax but requires only one time injection.

As of this writing I am not aware of a plan to release Volite in the US - this may be because it may be effectively the same product as an existing US-based Allergan product or because no product announcement has been made. Vollure and Volbella were just released in the last year or so, and they are both variations on the Hyaluronic Acid active ingredient. Frequently, the European versions of Allergan products are largely indistinguishable from US products other than being called different names (for instance, Ultra 2 and Ultra 3 in Europe vs. Ultra and Ultra Plus in the US). At the end of the day, it's more an issue of technical prowess of the injector and using the right quantities in the right locations...