The Youtube channel Engineering Explained went over the Tesla Semi, and the weight of the EV cab should be pretty similar to an ICE cab. Also EV trucks are allowed another 2k pounds.
There were about 10-12 concrete barriers as load in the demo each weighing 39,000lbs. So the weight being carried is around 40ishK lbs. So rough approximation - half the weight of the truck is load and half is the truck itself.