This answer, like many in life, can best be found using google (or any of their competitors)

Here is a list of the various eateries at JFK:
http://www.panynj.gov/airports/jfk-s...-services.html

Googling "Kosher Food JFK" yields the following:
http://yeahthatskosher.com/2011/12/k...-jfk-terminal/
http://www.jfkshul.com/about-us.html
http://koshernexus.org/general-topic...wark-airports/

One can also order food delivered from off-airport:
http://www.seamless.com/queens/john-...irport/kosher/