Have you ever heard the suggestion that very occasionally crops up "try not to read anything while you're writing, because the influence of it will affect your writing"? It's nonsense of course, at least on the level it seems to be aimed at. The idea that you could write something entirely free from influence just doesn't work, given that you've spent a whole lifetime being influenced, not just by books, but by other forms of media, people in general, and so on.
There are a couple of weird ways in which it has a point though. Firstly, whenever I've just read the work of a favourite author, my own writing will tend to edge just a smidgeon more in their direction. Not enough to help, usually, but enough to affect the emphasis of things and the rhythm of the writing.
Secondly, there is a tendency for time spent reading to take away from time spent writing, at least with me. Now, reading is one of my favourite things, but it does seem to occupy the same sort of 'headspace' used by writing. If I read until I'm tired of it, then writing won't immediately occur to me as an alternative. Sometimes, cutting back on one can help the other.
Finally, there's what I like to think of as the Jeff Beck factor. I should explain. There are several guitarists who have said in interviews that, after they heard Jeff Beck play for the first time (you'd think it would be Hendrix, but usually it's not) they then didn't feel 'worthy' to play their instrument for days or weeks after. Sometimes, if you read a really good book in the same genre, there's a part of you that just goes "I'll never be able to make mine that good", and that can set you back. Or worse, make you stall completely.