If Itachi is the servant of evil who Len sings about? No. "Servant of Evil" is a song Len sings. It's the सेकंड part of the "Story of Evil" series with the first being "Daughter of Evil". Len's character in the "Story of Evil" series is the servant to the क्वीन (Played द्वारा Rin)
Plus, why the hell would the song be about Itachi? Len has no idea who Itachi is. He's not even an ऐनीमे character. He's a Vocaloid.
But if the role as "servant of evil" MATCHES Itachi is a different thing. There are small things that match. Such as Itachi loved Sasuke और than anyone and anything, just like the servant of evil loved his twin sister - the daughter of evil (Yes, Len and Rin's characters are twins in the "Story of Evil" series).