Change Date Dropdown on Gravity Forms https://www.gravityhelp.com/forums/topic/date-drop-down-future-dates
add_filter('gform_date_max_year', 'change_max_year');
function change_max_year($max_year) {
return date('Y') + 7;
}
add_filter('gform_date_min_year', 'change_min_year');
function change_min_year($min_year) {
return '1977';
}