To me it sounds like a synthetic choir layered with some very soft high arpeggios.
A lot of the magic in this sound comes from the processing that layers it together, and what that processing is doesn't matter because there are many ways to achieve similar sounds. In this scenario I would imagine that lots of long shimmery / plate-like reverb would do the trick, maybe pair it with a swung or non-evenly divisible delay (per immediate measure, so like dotted notes) for some more movement.
I'd also say it's fair to cut a bit of the lower frequencies out, since in context of the song it may be used in it shouldn't be taking up much frequency range.
