Upgrade mac mini mid 2011 to 16GB

Yes. The following is one well-respected source: https://eshop.macsales.com/shop/memory/Apple_Mac_mini/DDR3_1333

Also see instructions in Upgrade or install memory in your Mac mini - Apple Support

Yes the 2011 Mac Mini can use 16GB of RAM.

However because Mac’s are picky, I would recommend using OWC or Crucial modules.

https://eshop.macsales.com/shop/memory/Apple_Mac_mini/DDR3_1333

https://www.crucial.com/catalog/memory

FWIW, can verify it as my 2011 MacMini has 16GB of OWC RAM.