Yoshi P has said it has happened before, something along the lines of "well, the money will be going back into the game next time..." in regards to Stormblood's development. So yes, there is proof. It was also obvious with how sparse things got during HW when they put FF XV as their priority to get it shipped. After it was released FF XIV got a little better. Connection? I'd say so. And I'm sure it's ongoing since XIV is lacking in more than a few areas despite the fortune I'm sure the game makes from the Mogstation daily/monthly.
