Sarada is FASTER than Itachi.
She has more POWER behind her attacks.
She wields a Mangekyou Sharingan, which gives her a massive resistance to powerful genjutsu’s, and allows her to break out of them. Kinda like how Sasuke’s BASE Sharingan broke out of tsukuyomi.
She also wields OHIRUME, an MS ability that can generate condensed spheres of pure gravity, that can suck away any attack like Ryu’s Iron Sand, and crush or tear apart someone with pure gravitational force. This negates Amaterasu and would give her an advantage over Itachi’s Susanoo.
And she is Also fighting people leagues stronger than Itachi, like Hidari, the Shinji clone of Sasuke, who has long since surpassed Itachi.
Seems to me Sarada has the shown capabilities to take on and beat Itachi.