Move the gallery tab to a not shown on profile position. Next create a new tab and title it Gallery then add a gallery field to it followed by setting its Asset to "profile". Next for the fields layout override parameters you can use the below to condition the galleryes display for the profile value layout.
[cb:if user="#me" user_id>"0"][value][cb:else]Please login or register to view this gallery.[/cb:else][/cb:if]
See the below tutorial for further substitution usage information if you want to adjust the conditions further.
www.joomlapolis.com/documentation/279-community-builder/tutorials/18353-using-substitutions-throughout-cb