A recent Geekbench listing clearly reveals an Android 8.0-powered Moto Z Play unit.
That was further confirmed by a screenshot of the handset's 'About Phone' screen, which also reveals Android 8.0 OS. In addition, the image also shows the device running the December 2017 security patch.
Sadly, there's no information on exactly when the update will roll out yet. Hopefully testing goes smoothly and it doesn't take too long.