Most main characters in the Narutoverse have more stamina than Itachi. It's never been a secret that his stamina is not his strong suit. He's not a go charging into battle and **** the world up fighter like Naruto, Sasuke, Madara, Hashirama, etc. His fighting style is much more similar to Shikamaru's-assess your opponent, find their weakness, use your resources, and end it as quickly as possible.
Besides Itachi left the manga back when people could still run out of chakra. At this point everyone seems to have a near infinite chakra pool and if they don't they can just get chakra from someone with a near infinite chakra pool. Seriously after a fight with Juubi, Juubito, Juubidara, then Kaguya all back to back to back, I really don't think that there's any way Naruto and Sasuke should still be standing, much less fighting each other now.