It's apparently supported (so says zfsonlinux.org) but I wouldn't use it for anything you care about without ECC ram -- I'm willing to bet these have cheapo controllers which don't support that though..
Well, I would be more hesitant to use some other file system without ECC RAM than ZFS. However, "these cloud servers are backed by Cavium ThunderX SoCs, high end processors designed for the cloud, and DDR4 ECC memory," says the article. Nevertheless, I would not consider ZFS on these to be "production ready" except for very small values of "ready."