Windows Server 2008 R2 Hyper-V on a Mac Mini
The short answer is yes. 

According to the official Hyper-V system requirements page, in order to run it you need a processor that supports Intel-VT (Virtualization Technology). Most processors today support this, but to be sure I checked on the official Mac mini tech specs page as well as the Intel's list of processors that support Intel-VT. 

From this, we can see that the i5 processor found on the Mac mini supports Intel-VT. I recommend upgrading the RAM if possible. Also, make sure that you are running one of the supported operating systems for Hyper-V. Hope this helps.