Well, you haven't been very specific on the time period of the fight.
In the early Naruto series, such as before and slightly after the Chuunin Exams, Jaraiya would crush Sasuke into little bits of dust. However, in Shipuuden it'd be a tough call. They would probably come extremely close, but no doubt Sasuke would pull some sort of trick out of nowhere and win.
Hmmm Sannin vs The Uchiha Genius, I would say Sasuke just because of his Sharingan(Third Tomoe) slowing down his movements. I don't think Sasuke would have to much trouble with Jiraiya's toad summons especially if he activates CS2 form.
No matter what time or series you discuss, this fight has only one possible outcome, Jiraiya winning.* We have seen a few toad summons, and we have seen a few other techniques, but he hasn't shown what he can do yet.* Itachi Uchiha has stated that he himself couldn't stand up to Jiraiya, now how is it that someone who needs a team to take down Itachi, could take down Jiraiya single handedly?* What it comes down to is this, Naruto and Sasuke will battle.* During that fight, Naruto will discover a power that not only puts him above Sasuke, but above Jiraiya as well.* That single moment will tip the balance of power in the Naruto universe, and until then and after, even with the Cursed Mark, there is no way Sasuke could overpower or hope to stand up to Jiraiya.* Besides, don't bother quoting Orochimaru's defeat in this one, we all know that rock doesn't beat paper as I stated in my blog topic, and even with that significant error in judgement by Orochimary, he was at a serious disadvantage due to his severly ailing health.* That is it, next fight please.* This one has been decided.
Itachi could not take on Jiraiya at the state he was in because he exhausted his chakra from using his M. Sharingan. Also even if they did fight, Sasuke would win because Kishi would just give him a super duper power to defeat him.
EHHH Wrong.* Read my blog post on Itachi and you will see what I mean http://www.hokagesroom.com/naruto/bl..._entry_id=3177*Itachi could say he was tired, but even then, he did lure Jiraiya away from Naruto, and admitted to Kisame that there reputations were mere shadows in comparisson to his.* Sasuke if far too young to face Jiraiya and Itachi has lost his edge, plateauing much too early to grow any further as a Ninja.* Besides, Sasuke would need that team to stand up to Jiraiya, and with his Toad Summoning abilities, the Perverted Hermit could easily summon his own team to outweight those numbers.* Then again, just Gamabunta alone could make Sasuke rethink taking on Jiraiya.* Even if the Uchiha could summon Manda (which hasn't been seen), we all know what happens to those Manda doesn't like or feels is too weak, then Sasuke would have to deal with another problem instead of just Jiraiya and Gamabunta.