True we cannot assume he has other Genjutsu, but i dont think Kishi would make Itachi say "It's not just these eyes, i can use to cast Genjutsu", if he can only use 2. Itachi has been praised for his Genjutsu abilities, and i don't think all of it goes to his Sharingan. But like i said, the Genjutsu he used on Naruto wasen't a particular Genjutsu.
It's not like that Genjutsu was called" Make Naruto think Sakura/Garra/Sasuke/Kakashi appeared on him" No. It was just a Genjutsu which makes you believe anything Itachi wants you to experience. He even made Naruto believe crows turned into Shuriken, at stabbed him. And even made it appear as if he was floating and dispersed into crows. So actually that wasent just a particular Genjutsu. It was an Genjutsu which he makes you believe something happens or happened, like all of his other Genjutsu does including Tsukiyomi. The only Genjutsu Itachi has, that has a name is Tsukiyomi.
And even if Minato had a Genjutsu defense, he has to first notice that he's even in a Genjutsu. And that would be nearly impossible without a Sharingan, unless Itachi makes the Genjutsu obvious by changing the surroundings, and making some crazy stuff happen. Other than that, Minato would be cluelessly trapped in a Genjutsu, and would probably Rasengan Itachi, thinking he hit Itachi, and that would leave him open for an attack. Or he can just use techniques inside the Genjutsu to cause pain and fatigue to Minato. And even if Minato knows how to escape, it would take concetration and time without a Sharingan. And NAruto even tried to concetrate and release it, but couldn't, since Itachi was making Shuriken stab into Naruto, breaking his concetration. SO escaping ITachi's Genjutsu is a fight within itself. And if you escape he can just cast another. And wouldn't even be drained, since it's not Tsukiyomi.
And if Tsukiyomi gets Minato, which it proabably would he's most likely done, since even Kakashi sharingan was useless. And it's stated who can break Itachi's Tsukiyomi. And Minato dosen't meet the stated requirements.
But Itachi's only hope is to use Genjutsu at the beggining of the match which he probably would. other than that Itachi loses, since Minato can dodge Amaterasu, and Susano'o, and Ninjutsu attacks, and Itachi's Taijutsu