I don't know the numbers, but at least some of Uber's tech employees are working on things that aren't directly connected to the app and rides, like mapping and self-driving cars.

One of their recruiters contacted me a while back, and it sounds like they're working on some really neat stuff, but I don't agree with all their business practices, so I didn't pursue it :-/ In any case, he pointed to their website: https://www.uberatc.com/