Core iQ does support GIF files within all of our email templates, and they can be uploaded just like any other image. Just upload the GIF file to the Template Library of the email template you are editing, then click the Copy URL button, and place the image in your email template. Core iQ will display the animated image in the Desktop Preview, giving you a good idea of how your email will look on a desktop mail client.
The only thing to be aware of is that some versions of Outlook do not support GIF file animation. They will only display the first image file within that GIF, meaning that a static image will display instead of the animated one. This only means that if you have customers using this email client, be sure that the first frame of your GIF also works as a static image.