There is evidence, but it's relatively weak from statistical significance point of view. This is also true of Saez's claims, such as if only we get rid of lowe

There is evidence, but it's relatively weak from statistical significance point of view. This is also true of Saez's claims, such as if only we get rid of lower taxation on capital, things will improve for the 99%. I am not aware of any evidence that would support this prediction.