SEO Tip #40: How many pages can Google index from a single site?
Matt Cutts: Wow, good question. Not that I am aware of. We will index millions of pages if we think a site is sufficiently good and has a sufficient amount of content.
You are very unlikely to bump up against a limit in our index. It’s purely how useful we think your pages are, which is determined in large part by how much PageRank you have, how many people link to you and what the reputation of those pages is.
So if there is a limit I’m not aware of it. I really kind of doubt that there is. We tend to just crawl as much of a site as we think we can use and we budget that relative to all the other sites and how useful we think a site is and how many people are linking to it.
So as far as I’m aware there’s not a limit, and hope that helps.