Based on the official documentation, the combination of TFS 2013 and Visual Studio 2017 can count on high level of support. Later in the same article, you'll find the description of that term. In particular:
If you are using newer versions of Visual Studio against older versions of Team Foundation Server, you can similarly expect most features to be supported.
However, you should still consider upgrading the TFS instance on a regular basis, since the distance between VS and TFS versions will increase if you only upgrade VS, and thus the level of support will decrease. Take a look at the first image in this article to understand the upgrade path you should take.