How can I share a form with another user's Jot Form account?

If you want to share access to your copy of the form, you can add the other account as a sub-user:

https://www.jotform.com/help/232-How-to-Share-Forms-with-a-Sub-Account-User

If you simply want a to copy the form to the other account so they can have a copy of their own, here is how to do so:

https://www.jotform.com/help/42-How-to-Clone-an-Existing-Form-from-a-URL