Do Google's search ranking algorithms factor in your usage of H2-H6 subheadings? See the evidence for and against this theory.

Google’s search results are full of web pages that do not feature H1 headings or that use them for styling purposes (a misuse of the heading tag!).

Hi guys,I'm writing a html to pdf converter in Ruby. My problem is I don't know what font size to use when I parse a heading tag such as H1 or H2, etc ...