Else If statement for ACF [closed]

You’re mixing curly brackets and another syntax. This should help:

<?php
if(get_field('hero_video', 'option') ) {
     $headervideo = get_field( 'hero_video', 'option' );
     echo '<div class="headervideo">' . $headervideo . '</div>';
} elseif ( get_field( 'hero_upload', 'options' ) ) {
     $headerupload = get_field( 'hero_upload', 'option' );
     echo '<div class="hero-video" data-vide-bg="mp4: ' . 
     $headerupload . '" data-vide-options="loop: true, muted: true">
</div>';
} else {
     get_field( 'header_image', 'option' );
     $headerimage = get_field( 'header_image', 'option' );
     echo '<img class="headerimage" src ="' . $headerimage['url'] . 
'" alt="' . $headerimage['alt'] . '" />';
}
?>