If Voluma isn't injected deep onto the cheekbone, can it still provide a lift or will it just volumize?

Proper injection technique for Voluma requires that it be injected deeply into the skin, just above the bone. The needle doesn’t actually go into your cheekbone, however. Voluma in the cheekbones provides a nice lift to your face. Be sure to consult a board-certified dermatologist who’s an expert with Voluma. 

Voluma is a deep filler, and in general, though I like it very much as a tool, I don't think any filler really "lifts" tissues.  It gives the three dimensional visual apperance of contour having been lifted.  I suggest you speak with a good, honest plastic surgeon about your options, rather than try to micro-manage which layer Voluma is used in.

When injecting Juvederm Voluma or Restylane Lyft, the optimal technique is to place the filler in using depot injections on the bone. This gives the most lift and structural support to the cheeks. Other fillers such as Restylane Defyne could be used more superficial if need be but this is an area that the injections should usually be limited to periosteal (on top of bone) placement. 

Voluma is a very thick gel from the Juvederm family. Voluma has the ability to increase volume, but it has a very specific injection technique. It needs to be deposited in very tiny amounts just over the bone area otherwise it will create noticeable lumps and will not provide good esthetic results.