...program can't start because libgcc_s_sjlj-1.dll is missing

I haven't used any of Ruben's builds of MinGW, but I would have expected that there would be a libgcc_s_sjlj-1.dll in the same ('bin') folder as gcc.
Search the entire compiler tree for that file and, if you find it, add that location to your PATH.
I think you might find it in both the compiler's mingw\lib and x86_64-w64-mingw32\lib folder - in which case you just add either of those locations to the path.

This dll file is available in strawberry516

Best not to copy it across to a different compiler.
You could use the compiler that came with Strawberry instead of Ruben's, if you like. Just put the strawberry/c/bin folder first in the path.

However, Ruben's should be fine, I think ... once you find libgcc_s_sjlj-1.dll and add it's location to the path.

Cheers,
Rob