Whoa talk about bringing the dead back to life. Some of the members on this thread are downright ancient.
Itachi may have admitted he couldn't beat Jiraiya, but that could have been a very biased opinion. If Jman starts in SM with the 2 elders, its high difficulty for Itachi. Without SM, its no more than mid difficulty for Itachi. Engulfing Itachi's Susanoo with his giant frog stomach summoning is his only theoretical way to deal with it, but not a true counter.