I don't know if I do something  wrong, but when I set the aspect ratio in unity to 64x64 my 8x8 sprite still seems super small. 

Aspect ratio, or resolution? If you've just set a 64:64 aspect ratio, the Game tab will just pick a resolution that fits the tab that meets the aspect ratio (which is the same as 1:1). You'll need to set the resolution. But, keep in mind, you'll also need to think about resolution in the build as well.