Itachi's MS is a force too hard to handle for two Sannin. Tsukuyomi will restrict their latitude considerably, as they will be prepared to experience their defeat by a single eye contact with Itachi, which can be easily provoked by latter. Under this circumstance, they will furthermore lose their only possibility to keep watching on Itachi's Amaterasu, which in this case will doubtlessly surprise the both of them, at least ending in Jiraiya's certain defeat. His Susanoo makes his victory just more evident.
Jiraiya's and Orochimaru's skills and talent pale in comparison to Itachi's as well, that's beyond debate. When Itachi was able to put Orochimaru at his place with one ordinary Genjutsu without displaying further techniques or skills of him, Jiraiya is not strong enough to close this huge gap and outgo Itachi.
I recall that Naruto fell for Itachi's Genjutsu twice in their only two meetings after the timeskip, despite he was already aware of Itachi's Genjutsu and was prepared for it. That proves that knowing about his Genjutsu or being even confronted with one of them in the past doesn't prepare them for a second confrontation. Itachi, who is a master in the area of Genjutsu and possesses comparable skills in all the other areas, will find an opening to use a feint and cast a Genjutsu pretty easily. All this is within his capabilities as proved and hyped in the past several times.
