let choices = {
    'First Choice': "Are you sure you want to submit First Choice?", //change to choices and message for choice
    'Second Choice' : 'Are you sure you want to submit Second Choice?',
}
$('#gform_submit_button_'+GFFORMID).click((event) => {
    let radioVal = $('input[name="input_3"]:checked').val(); // change to name of radio button html element
    let mesg = '';
    if (radioVal in choices){
        mesg = choices[radioVal];
    }
    if (mesg){
        let confirmed = window.confirm(mesg);
        if ( ! confirmed ) {
            event.preventDefault();
        }
        else {
            $('#gform_'+GFFORMID).submit();
        }
    }
});