Chakra strength is a part of high stamina too, besides the chakra amount.
According to the databook Kakashi has a stamina of 3, so higher than Itachi but reach his limit much faster. The reason is the chakra strength which Itachi has as an Uchiha. The result of the chakra strength is, that someone like an Uchiha can use techniques with a lower energy consumption than a normal Shinobi.
Nagato has a very strong chakra too, thats a reason for his stamina too.
Now I see finally that you Nagato fanboys definitely haven't decent arguments anymore.
Accept the power of the Uchihas

.
Nope, Kakashi reaches his limit fast when he uses Kamui, which needs up much more chakra, because he is a nonuchiha using MS.
Stamina and chakra are nearly the same, high chakra=high stamina
Itachis stamina is his weakspot. Thats why he uses Genjutsus first, cause most genjutsus dont need up much chakra.
Beeing an uchiha is not=strong chakra (being Senju/Uzumaki=strong chakra)
Im Nagato fan, but also Itachi, Kakashi, Kyuubi, Killerbee, Mei Terumii, Rock Lee and Guy fan.
Its just that Itachi cant beat Nagato. You want to know?
Battle begins.
1: Nagato uses shinra Tensei, Itachi is blown away for example 50 metres.
2: Nagato summons his army of monsters
Itachi: askes himself what kind of power that was. He decides to test Nagato
3: Monsters are attacking Itachi.
3.1 Amaterasu (Itachi burns the summonings) or
3.2 Susanoo finishes the summonings off (exception the chameleon cause ts invisible, even to Rinnegan)
4. While Itachi burns the summons or fights them, Nagato uses chibaku Tensei. Sphere is flying into the sky.
5. Itachi is needs a few moments to notice the sphere, he doesnt know, what this is going to be (the summonings are dieing now)
6. Nagato maybe hides himself inside the chameleon or just stays back.
7. Chibaku tensei begins, Itachi notices the ground rising to the sky, he notices the strong gravital pull.
8. The sphere starts growing, while Itachi is pulled in. He realizes, that his only chance to escape is to destroy the sphere.
9: his strongest attack is not amaterasu: its that strange shurikan, his susanoo can throw. (Chibaku is growing rapide now, mountains and trees are pulled in.
10: My opinion is, tht his shurikan wont destroy the chibaku, since even the shots of kyuubi didnt crushed it at once. (Maybe a part is cut of, but nagato will just use more chakra, the devastation becomes bigger, the pull even stronger)
Result: The rock, Itahi stands on will break into its peaces, Itachi has no safe stand anymore, the speed of the attracted rocks increases dramatically, Itachi is smashed on the surfice of Chibaku. He uses Susanoo to try to protect him from the stones, that will impact everywhere.
The chibaku becomes larger and Itachi is closed in Stone. Susanoo can maybe withstand the pressure, maybe not.
It doesnt matter, after one or two minutes itahi cant keep up susanoo. =dead