Numerous studies have shown that there is a relationship between the amount of content on a page (typically measured in word count) and it's ranking potential - generally longer content will rank higher. Obviously content also needs to be topically relevant, keyword rich and highly readable for the visitor. Note, in our assessment, we look at all selectable text on the page at load time, not hidden content.
As a general guideline, it is recommended to have atleast 500 words of content on a page to give it some ranking potential. However this should be considered on a case by case basis. It may not be relevant for particular pages like 'contact us' pages for example.