The 8K is discussed a bit in this Edge Up Asus page, but I don't see refresh rate noted. DisplaySpecifications.com has a page on a 6K Asus that I presume is the one we're discussing, but I don't see refresh rate noted.
That said, the 8K looks to be targeting more professional users, a high refresh rate at these resolutions would be quite demanding on the interface (to convey it) and computer (to process and support it), and I haven't heard of either of these monitors being marketed for gaming (gaming seems to be a main driver for high refresh rates).
So if I were betting, my money would be on 60-Hz.
That said, the 8K looks to be targeting more professional users, a high refresh rate at these resolutions would be quite demanding on the interface (to convey it) and computer (to process and support it), and I haven't heard of either of these monitors being marketed for gaming (gaming seems to be a main driver for high refresh rates).
So if I were betting, my money would be on 60-Hz.