Will Turning Data usage off disable the hotspot?
Technically, yes.If you turn off the data plan, then regardless if they try to be a hotspot, it won’t matter because there won’t be a data plan to use.
However, (I know this because I was researching data plans last week) you can get a data plan that doesn’t have hot spot or tethering capability.  So, your user can still have mobile data, but they won’t be able to use their mobile device as a hotspot.   You also might want to ask the carrier if they can manually turn off the hotspot function.