Hello,
Yes, it's possible to use an animated GIF. The logo option within the Builder is found in part 2 - DESIGN. You can choose to upload a GIF there. However, you won't be able to preview the animated GIF. If that fails, you can also simply replace the LOGO.GIF file in the IMAGES FOLDER. You would need to log into the cPanel and use the File Manager. Your site is typically under the PUBLIC_HTML folder. There you can look for the IMAGES folder and then re-name or delete the existing LOGO.GIF file. You can then UPLOAD your Animated GIF file. Please bear in mind that the graphic file needs to fit with the template you have selected in the Builder. Otherwise, it could be more of a distraction than an identifying graphic that fits your website.
I hope that helps to answer you're question! If you have any further questions or comments, please let us know.
Regards,
Arnel C.