#facepalm. The manga stated the Yata Mirror deflects all things.
Use your head and deal with facts. Edo Madara genuinely cannot defeat Itachi and I'll tell you why.
1.All Madara's attacks (Susano'o sword, Yasaka's True Magatama, Mokuton Attacks etc) will be deflected by the Yata Mirror and you know it. #MangaFact
2.Madara has no answer for Itachi's Tsukuyomi (It was stated in the manga that only Itachi's own blood could break it, hence, the reason why Sasuke was able to break it) #MangaFact
3.Madara has never been seen using Amateratsu. Surely he wudda used it against the Allied Forces and Naruto (since amateratsu is perfect for opponents in large numbers) if he could. Itachi one the other hand can use Amateratsu although Madara would just absorb it. #MangaFact
4.And most importantly, Itachi has a sealing jutsu (Totsuka blade) which is the only thing that can truly end an Edo but Madara doesn't. #MangaFact
5.The only thing Itachi cannot counter is the meteorite jutsu but he doesn't need to counter it. He and Madara are edos so they'll both be destroyed and then come back #MangaFact
6.And if all these don't work, Itachi has IZANAMI. Madara is a proud god as we all know so no one is better suited to enter Izanami than him. #Mangafact
Sage Madara>Living Madara>Edo Itachi>Edo Madara>Living Itachi