Can I dual boot Mac mini with Windows 8?
Yes you can.

Windows 8 support was provided to Boot Camp in version 5, along with drivers for the Mac hardware.


  Boot Camp 5 adds Windows 8 (64-bit) support. Use the Boot Camp Assistant and a USB drive to install the latest Boot Camp drivers for your computer. These new drivers support both Windows 7 (64-bit) and Windows 8 (64-bit). You should download the newest drivers available any time you install Windows.


Source: http://support.apple.com/kb/HT5639

Per the quote above, you can use the Boot Camp Assistant to partition your drive, then install Windows 8 from ISO or disc.

You can find the full guide to installing Windows through Boot Camp on Apple's Help site:


Apple: Boot Camp Help: Install Windows on your Mac


To summarise:


Open Boot Camp Assistant from /Applications/Utilities/Boot Camp Assistant.app.
Follow the instructions to partition your disk.
Let it reboot using your install media.
Install Windows normally.