"Do you know if he is going to leave tomorrow?"
Translation:Ξέρεις αν πρόκειται να φύγει αύριο;
Will this translation work: "Ξέρεις αν αυτός είναι πρόκειται να φυγει αύριο;"
"Ξέρεις αν αυτός πρόκειται να φύγη αύριο;" The inclusion of thw word "αυτός" shouldn't preclude the translation from being accepted. It is optional to include this word in the Greek translation, and should be accepted as an alternative translation.