Lacking an exact measure that we can all agree on, "influential" is kind of subjective. So I'll contribute with my subjective opinion: Paul Graham's essays are (collectively) among the highest quality content that I have found on the Internet. They are the opposite of click-bait and attention-spam. I don't agree with everything Paul writes, but so far I have never regretted spending the time to read one of his essays. This is rare in today's Internet environment. I can only think of Scott Aaronson and a few others who are comparable. But to repeat myself, this is my subjective opinion.