Basically every site on the internet has 久米由基's given name as Yuuki/Yuki, including his Japanese Wikipedia entry (and our hiragana reading: Yuuji is surely a typo). However,
V-RARE SOUND TRACK 11 has a "Yoshiki Kume" who performs piano on the track that he arranged, track 2. According to his Wikipedia article, 久米由基 is a pianist. So, same guy, right?
I did a little bit of searching and couldn't find anything official confirming a reading of Yuuki. Bemani definitely isn't my strong suit, though, so if there's anything in an album or game or something that says Yuuki, let me know.