Hi absolutezero,
On WSUS server, in Products and Classifications, check window 8 and other related products you want, then click synchronization now.
After synchronization, you may find these updates, then on WSUS server, right click these updates, and click "Approve for install":

On clients, apply related GPO to configure Automatically update:
Configure Clients Using Group Policy
https://technet.microsoft.com/en-us/library/cc708574(v=ws.10).aspx
Best Regards,
Anne
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