I recently wrote a blog post coincidentally using Stack Overflow's own data to find correlations between the self-reported skill level of developers vs. other metrics such as salary: http://minimaxir.com/2016/07/stack-overflow/

The tl;dr is that yes, there is a positive correlation between developer skill and salary (http://minimaxir.com/img/stack-overflow/so-programming-6.png) for example, but it's hard to say which-causes-which.