Showing different images depending on user role

What’s the variable $user_info in you code? Probably you mean $commentator_info? If yes, this is certainly the error. You are trying to extract wp_capabilities (?) from a non-initialized variable ($user_info).

Try this:

    <?php
   $comment_id = get_comment_ID();
   $comment_data = get_comment($comment_id);
   $commentator_id = $comment_data->user_id;
   $commentator_info = get_userdata($commentator_id); // get_userdata, with the user ID specified, returns a WP_User object.

   if ( user_can($commentator_info, 'editor') ) {  // user_can accept the user ID or the whole user object ($commentator_info).
      // echo markup here
   }

Changes: added $comment_id and $comment_data variables (now it’s more readable), deleted $capabilities (you don’t need to store the capabilities in a variable, you can check them directly passing the whole user object (or the user ID) and the capability you want to verify to user_can(). Added user_can() and removed the array-key check.