Apperently a lot of supporters of jiraya's side still think that itachi and kisame ran away because they couldn't have beaten him, some only think that because the ANIME (which we are in the MANGA section, can we use the anime as a source?) saying they would be beaten is rock hard evedense he can't beat jiraya... even with another kage level partner(who can beat tailed hosts alone)
And before that they fought kakashi and asuma and kurenai (making sure they all lived as well) because they still had shit to do (find sasuke, "attempt" to catch naruto) the way it looked in my opinon, itachi could put all 3 of them down by himself with genjutsu,(so why run away when you can subdue without hurting them but make it look like your still a villian?)
He only had to use tskuyomi on kakashi because regular genjutsu is seen thru by a sharingan which kakashi is quite good with so itachi would have had to actually hurt him possibly kill him to move on
But even with sharingan no one but another MS sharingan uchiha, so at the time only madara could break out of his MS genjutsu alone (I still think he let sasuke out of it in there fight on purpose). So the tech for breaking genjutsu that jiraya teaches naruto wouldn't work when tskuyomi is in a league of its own. Itachi's mastery of it lets him put you in days and days of real mental torture that you can feel in seconds of real time.
by the time he could even start molding chakra the whole thing would be over
Then theres the idea that depending on how severe he wanted to make it, (because itachi's he can control the length and the method of pain) he might even break jiraya's will to fight, or slice his throat while hes in the jutsu so IF and only IF he could avoid genjutsu and some of itachi's other fast attacks, remember itachi's hands move faster then a reguler eye can see, kakashi only barely caught it, long enough to summon ma and pa and have them put him in sage mode could he distupt powerful genjutus or move out of amatsaru before it touches him.
So yeah if you start it off with jiraya in sage mode with the frogs on his shoulders and knowledge of how all 3 MS jutu works, then he wins, if hes lacking sage mode at the start, its over in seconds with itachi winning...in my opinon