function wpf_custom_access( $can_access, $user_id, $post_id ) {

    if ( wp_fusion()->user->has_tag( 'Cancelled Member', $user_id ) ) {
        return false;
    } else {
        return $can_access;
    }

}

add_filter( 'wpf_user_can_access', 'wpf_custom_access', 10, 3 );