{% if site.google_analytics %}
    <!-- Google Analytics (http://google.com/analytics) -->
    <script>
    /*(function(i,s,o,g,r,a,m){i['GoogleAnalyticsObject']=r;i[r]=i[r]||function(){
    (i[r].q=i[r].q||[]).push(arguments)},i[r].l=1*new Date();a=s.createElement(o),
    m=s.getElementsByTagName(o)[0];a.async=1;a.src=g;m.parentNode.insertBefore(a,m)
    })(window,document,'script','//www.google-analytics.com/analytics.js','ga');
    
    ga('create', '{{ site.google_analytics_id }}', 'jekyllrb.com');
    ga('send', 'pageview');*/
    </script>
{% endif %}
{% if site.google_analytics %}
    <!-- Google Analytics (http://google.com/analytics) -->
    <script>
    (function(i,s,o,g,r,a,m){i['GoogleAnalyticsObject']=r;i[r]=i[r]||function(){
    (i[r].q=i[r].q||[]).push(arguments)},i[r].l=1*new Date();a=s.createElement(o),
    m=s.getElementsByTagName(o)[0];a.async=1;a.src=g;m.parentNode.insertBefore(a,m)
    })(window,document,'script','//www.google-analytics.com/analytics.js','ga');
    
    ga('create', '{{ site.google_analytics_id }}', 'jekyllrb.com');
    ga('send', 'pageview');
    </script>
{% endif %}

Remove comment around Google Analytics code.
Remove comment around Google Analytics code.