I thought about that too, but then i asked myself, what was the purpose of lying in that situation?Let's not forget Itachi has lied alot in the show so maybe he lied about that too.
Madara was since long time ago dead. He never met Itachihe was trained by madara like he said. learned all the secrets to the sharingan like madara
He found a 13yo Obito in a cave where he admitted himself that he could not move, and died short after that. At that time, Itachi was 4he found obito thats means he wasnt long since dead