I looked in the NSDAR Patriot Index and did not locate Joseph Gordon. That doesnt mean he didnt fight, it means that no one has joined the NSDAR Membership using his lineage. Here are some additional links that might help with your research.http://valleyforgemusterroll.org/
Both are databases of Pennsylvania militia.
Hope this helps and if we can help you again, please feel free to contact us.
DAR Volunteer Information Specialist
This is a free look-up service provided by DAR volunteers at the DAR message board.