ACF Repeater Field, need IF statement for if sub field has content

As seen on ACF documentation, to check for a value before displaying it, simply use:

<?php if( get_field('field_name') ): ?>
    <p>My field value: <?php the_field('field_name'); ?></p>
<?php endif; ?>

So in your case, you are already getting the sub_field into $instruction, so simply use this:

 if( $instruction) ) :