It works following the official guide:

    https://github.com/bitcoin/bitcoin/blob/master/doc/build-windows.md

But first you have to build a static version of Qt5.7 by following the guide (it takes some hours):

    http://dimitris.apeiro.gr/2015/06/24/build-a-static-qt5-for-windows-by-compiling/

And copy all the files from:

    C:\Qt\Qt5_static\plugins\platforms

To the bitcoin source folder:

    [whatever]\bitcoin-0.13.2\depends\x86_64-w64-mingw32\plugins\platforms