Elaina is Saya's crush. No doubt. The anime is very clear about this and even uses it for humour development. But Saya is, at least, someone very special to Elaina too.
In the last episode, we can see that Elaina not only ACCEPT Saya's present (the matching pendant) but she USES IT all the time.
When Saya investigates about that kingdom where nobody can lie, Elaina helps her without she even ask. Taking in account how narcissistic Elaina is, and how she's careful about being involved with something, that is very interesting.
For me is enough for ship. I want more of them.