Hmm.. Interesting, although unfortunately that the only thing you have to said about Jiraiya was his achievements on Naruto.. How about Minato, Nagato, Konan...
You also used allot of quotes that other people have said yet Itachi himself stated that he wouldn't win. Never the less... He never guided Sasuke through hatred. He was the one that destroyed his life.
Itachi is the solo reason that he was driven by hatred, He's the reason he has no friends... He's the reason that he turned against the village. He may have gave him a power-up although that's got nothing to do with itachi's achievements, as those powers are being used to go against everything itachi stands for... (Destroying the village).
I believe that it would be an incredible fight between them, as we never got to see much of Jiraiya fighting in his prime, or got to see all of his techniques. However, we got to see all of Itachi's techniques more and under different circumstances.
Jiraiya was the one that will have essentially saved the world, as he spend his whole life searching for that one savior. He luckily found him (Naruto Ukumaki).
Good thread though!