Hi,
have you tried to do something like this?
<div id="map1" class="acf-map col-lg-7 bgImage" data-zoom="14">
<?php
$location = get_field('google_map_location');
if( $location ):
$gm_headline = get_field('gm_headline');
$gm_description = get_field('gm_description');
?>
<div class="marker" data-lat="<?php echo esc_attr($location['lat']); ?>" data-lng="<?php echo esc_attr($location['lng']); ?>"></div>
<?php endif; ?>
</div>