I bet it's the same as the Sony-mount version. I think that we'll see some of that now, just as we're seeing Sigma use the same lenses in various mirrorless mounts (the 16, 30, and 56 come to mind for the M). Optical design isn't going to change, just the mount.
Ok, so I went to Samyang's page and got the optical drawings for the new RF mount lens, and for the Sony E lens. It's weird - they're the same, but different. They changed the color coding for the different types of glass, so that can throw you off if you don't pay attention. The only real difference I see is that the RF version has one element with "HR" glass. (Samyang calls it "high reflective" though that seems to me to NOT be what you would want - maybe the translation was botched, and it should be "high refractive", but what do I know).
The RF first, then the Sony E mount.
I guess we wait and see what comes when the lens hits the streets...