No modern tanks have toilets and I've never heard of any older ones having one either. I'm pretty sure this cutaway of the Maus is speculative, the only surviving example of it had the inside bombed out so the Soviets couldn't capture this utterly-amazing-and-not-at-all-useless technology.

Edit: That being said British tanks have had electronic tea makers since 1945 when the Centurion was introduced, which is equally hilarious to me