This is so pointless, but its more than obvious that Itachi would win. With or without genjutsu he is still the superior shinobi here.
gaara can win without the threat of a instant killer genjutsu it makes it soo much more easier to win for gaara he stopped a enraged raikage in his ration shield powered liger bomb drop who had the intent to kill sasuke with his sand he saved the sand village from deidoras bomb with his sand and gaara has been shown to block amaterasu itachi is smart smarter than gaara but gaara isn't stupid he can just hover in the air in his sand dome sheild use his third eye to view the battlefield / itachi and attack whilst defending at the same time if it soo happens itachi gets up close gaara has his automatic shield and at worst his Armour of sand
umm i am sorry for puting a piontless fight up how is it piontless idk but i rekon minato vs itachi is more piontless just cause minato is sealed away for ever and people stil argue bout that so why not this??