Does Gilgamesh stand up for himself in the Epic of Gilgamesh?

I'm not sure what you mean by "stand up for himself". In my opinion, Gilgamesh grows and changes, he learns how to be a king.... a leader, a man who will put his people first. We might say he stands up for himself when he rejects Ishtar, knowing her wrath will be immense. He will not give into her or accept her promise of great riches and rewards. He follows his heart, which is in essence standing for himself.