We know that during the ~3 months before the Pro's release the Xbox S outsold the PS4 in the USA, and we know both Playstation models sold 6.2 million units between mid-November (Pro's launch) and end of December.
In anticipation for the Pro, fewer people bought Playstations. After the Pro was released, Sony sold consoles at one of their highest rates so far.
IIRC Sony dropped the price on the slim right around Black Friday so i dont think the Pro alone was the driving factor behind the sales uptick, people look for good deals around holiday season. I believe from reading the NPD thread on gaf that Pro was 10% of PS4 sales