Many webmasters are of an opinion that a site can automatically rank better just by having a lots of pages. But, this is not the case with Google. A site cannot rank better just by having a lot of webpages, instead it may rank well if more pages leads to more links and a higher page rank. This is what Matt Cutts is suggesting in the video given below:-
More webpages may lead to more opportunities of getting links and different webpages may also serve different set of queries that may help it to rank. But simply because your site has a lot of pages does not automatically provides a boost in ranking.
Also See:-
How to Calculate KEI?
Seo Tools
Keyword Density
Seo Tutorial
What are Doorway Pages?
Keyword Stemming
How to Find Out Which Keywords You Rank For
Using Google Trends to Find the Popularity of Keyword
