gform_pre_submission_filter

/ add conditional logic for the notification message
add_filter('gform_pre_submission_filter_1', 'conditional_message');
function conditional_message($form){
}

        // append a different html text for payment options
	if($choice1)
		$form['autoResponder']['message'] .= "<p>Here I insert Text 1</p>";
	if($choice2)
		$form['autoResponder']['message'] .= "<p>Here I insert Text 2</p>";

        // return modified form
        return $form;