It has to have been pretty huge. According to the 2020 Philpapers survey, over 66% of philosophers are atheists - the vast majority of those atheists believe evolution is the driver for diversity of life on earth, and that Humans are the product of evolution from other previously existing species.
I'd be willing to bet that the percent of philosophers identifying as atheists shot up drastically as Evolution gained popularity among scientists.
Understanding humans as evolved creatures would also have been a source for many new papers and ideas on ethics and morality, social behavior, psychology, and probably politics, to name just a few affected topics within Philosophy. Understanding humans as evolved creatures could also have a profound impact on how philosophers view the relationship between humans and other life on Earth, including potentially moral responsibilities to those other creatures.