itachi himself said jyria was stronger than him
Itachi also said that it wouldn't have mattered if he and Kisame had reinforcements. Come on now, don't be a fanboy, everyone admits that what Itachi said was just him trying to get Kisame to leave Konoha.
If you think about it, Itachi could have killed Jiraiya right then. Easily.
He was taring straight at him, making eye contact for Tsukuyomi. If he used Amaterasu down the hallway, Jiraiya also would die that way. Itachi had Susanoo as a backup to protect him from the toad gourd prison and to seal it and Jiraiya.
No everyone knows that Itachi was lying. Everyone except for you apparently.