Pushing PHP variables to dataLayer using JS

I heard from a good friend that people in this community can be very helpful and good-hearted so I'd love some help from you peops!

I've been trying to push php variables to the datalayer using the .push() method in javascript (for google tag manager and google analytics). Below is the code snippet to better understand what's happening.

 <?php . . . . . . ?>
    
    <script language='javascript'>

     $(window).on("load", function() { 

     var variable1 = <?php echo $variable1_php; ?>;
     var variable2 = <?php echo $variable2_php; ?>;
     var variable3 = <?php echo $variable3_php; ?>;

      window.dataLayer.push({
             'event' : 'eventName',
             'variable1_for_gtm': $variable1,
             'variable2_for_gtm': $variable2,
              'variable3_for_gtm': $variable3,
});

});

</script>;
        
    <?php . . . . . .

What am I missing exactly? Thanks a lot!! P.S. Other events are correctly being tracked by GTM and recorded in GA.

source https://stackoverflow.com/questions/71196963/pushing-php-variables-to-datalayer-using-js