It is recommended to have the same fields in the Gravity Forms form as the Mautic form. But you don’t have to create a form twice. CampaignSuite has the option to copy a Gravity Forms form to a Mautic form in one go.
Select a form from Gravity Forms and choose whether it should be a Standalone or Campaign form in Mautic. Then click on Create a form .
Now a new form has been created in Mautic with exactly the same fields as the Gravity Forms form.