    <section id="sponsors" class="container-fluid content-section text-center">
        <h2>Our Sponsors</h2>
        <div class="row">
            <div class="col-md-4"></div>
            <div class="col-md-4">
                <img class="sponsor-logo" src="{{ site.baseurl }}/img/betomall.png">
                <h3>Betomall.com</h3>
            </div>
            <div class="col-md-4"></div>
        </div>
    </section>

    <section id="sponsors" class="container-fluid content-section text-center">
        <h2>Our Sponsors</h2>
        <div class="row">
            <div class="col-md-4 col-md-push-4">
                <img class="sponsor-logo" src="{{ site.baseurl }}/img/betomall.png">
                <h3>Betomall.com</h3>
            </div>
        </div>
    </section>

Use col-md-push-4 to properly centre the column
Use col-md-push-4 to properly centre the column