What they can do is assert that some critical part of technology that uber has access to originated at waymo and was brought to uber by whoever brought it there - in an illegal way.
If that's the case, they can be both forced to pay damages and be forced to turn over (essentially delete) the things they are in possession of that are not "theirs". In that case, anything that uber has developed "on top of" what had been stolen, could be assigned to waymo as well. Practically, this is just all settled with money. they won't run back and forth with data and software. Waymo gets however much they are assigned in damages and Uber will be told to not use these things anymore.
That can easily shut the whole Uber self driving car operation down - or cripple it so much that continuing won't be feasible because they would run out of money first/be unfundable.
The guy who actually stole things from Waymo is obviously going to have a bad time because he did (allegedly) commit a crime. In the "innocent until proven guilty" way. I don't know what he has or has not don, but if he did take trade secrets with him, thats going to be a problem.