Although Huawei recently claimed that its handsets currently running EMUI 5.0 would not get EMUI 5.1, an updated Mate 9 has been spotted in the wild by a member of the well-known XDA Developers community.
http://www.notebookcheck.net/Huawei-Mate-9-with-EMUI-5-1-spotted-online.221720.0.html