Whether or not Ikuhara was the inspiration behind Kaworu remains to be seen, but it’s fun to thing that one of the greatest directors in anime directly influenced another one of the greatest anime directors for one of the most popular characters ever created.
For years, it has been rumored that anime director Kunihiko Ikuhara, known for Revolutionary Girl Utena, Sailor Moon, and Sarazanmai, was the inspiration for Kaworu Nagisa in Evangelion.
Ikuhara does mention that Kaworu acts more like Anno rather himself.