Gaara did look into both Sasuke and Madara's eyes and that will get him killed against Itachi.
Totsuka can also go through sand as far as I know.
However, if Gaara has a moment of brilliance and instead of looking into his eyes or standing still he takes to the skies and begins assaulting Itachi with sand torrents, he could win.
Desert or not, Gaara wins.
woah! no way he has minimal knowledge on itach and he makes the mistake of looking in a uchihas eyes, BIG MISTAKE on itachi especially since hes a standing target? gaara stands no chance without the desert
It depends. If Gaara knows everything about Itachi's abilities he will start with the 3rd eye and sand shield.
Knowledge:
Both - Gaara high diff
Gaara only - Gaara mid- high diff
Itachi only - Itachi mid diff
dusk crow illusion even with knowledge is hard to counter for gaara and amatarasu defeats gaara unless he has sand armour (sasuke kage submit used eton bullet not a proper ammy that appears on the target)