gform_review_page

add_filter( 'gform_review_page', 'your_function_name' );

add_filter( 'gform_review_page_6', 'your_function_name' );

	array(
		'content'        => '',
		'cssClass'       => '',
		'is_enabled'     => false,
		'nextButton'     => array(
			'type'     => 'text',
			'text'     => __( 'Review Form', 'gravityforms' ),
			'imageUrl' => '',
			'imageAlt' => '',
		),
		'previousButton' => array(
			'type'     => 'text',
			'text'     => __( 'Previous', 'gravityforms' ),
			'imageUrl' => '',
			'imageAlt' => '',
		),
	);

add_filter( 'gform_review_page', 'add_review_page', 10, 3 );
function add_review_page( $review_page, $form, $entry ) {
    // Enable the review page
    $review_page['is_enabled'] = true;
    if ( $entry ) {
        // Populate the review page.
        $review_page['content'] = GFCommon::replace_variables( '{all_fields}', $form, $entry );
    }
    return $review_page;
}

// NOTE: Update the '221' to the ID of your form.
add_filter( 'gform_review_page_221', 'change_review_page_button', 10, 3 );
function change_review_page_button( $review_page, $form, $entry ) {
    $review_page['nextButton']['text'] = 'Review & Submit';
    return $review_page;
}

gf_apply_filters( 'gform_review_page', $form['id'], $review_page, $form, $partial_entry );