There is no straight forward response to this query which has been flooded recently in various SEO chat forums. Even the response from Google’s Matt Cutt seemed quite vague. He mentioned quite a few number of times that having a large website with a lot of web pages doesn’t directly affect the PageRank but it helps the SEO professionals to leverage the SEO techniques and target for more keywords than they would with smaller websites.
This means your PageRank doesn’t have any direct relationship with websites having a large number of pages. The most important factor is to focus on optimizing each page of your website properly for search engines. As Google has been emphasizing on content for last few years, a smaller website with high quality original and fresh content could easiy have a higher PageRank than a large website with irrelevant or duplicate content.
So, at the end of the day if you are focused on creating lot of web pages on your website without optimizing each of the pages and having original content in it, your effort will be in vain. Rather you can work on improving the search engine ranking with an appropriate keywords analysis, sparingly using your keyword over the content maintaining the keyword density and search engine friendly website design for easy user navigation, crawling and indexing.