For now just hang in there, in the interim you'll need to use an alternative publishing tool or go to blogger.com to post.
The issue is currently being fixed in Open Live Writer, there has been progress even in the last few hours, so hopefully it won't be too long before it's ready. You can find updates to the work here: https://github.com/OpenLiveWriter/OpenLiveWriter/pull/101
It's not directly related to Windows 8 support, the Blogger authentication issue affects everyone. That said, apparently the OLW team are focusing on Windows 10 although it should continue to work OK on Win 7 & 8 as well.