I get more readers at AO3 than on Dreamwidth. Given that I mostly write in smaller (but still western mass media) fandoms, since I'm not on LJ and not spamming posting links to my fic to the multiple relevant communities for my fandoms there most of my readers who aren't amongst the < 100 people in my DW circle (and the smaller portion thereof who read fic and in my fandoms) come from people who go through AO3 by fandom or by tag and stumble upon my dreck.

If you're on LJ and in big fandoms where you can post about your fic in a main comm, a fic comm, a comm just for your pairing, maybe in a kink meme and so on, AO3 isn't going to be a significant traffic driver.