Show only the future event (Advanced Custom Fields)

You need a meta query. There’s also documentation on ACF for querying dates.

<?php

$event = new WP_Query(
    array(
        'post_type'       => 'gacr-event',
        'posts_per_page'  => 5,
        'orderby'         => 'meta_value_num',
        'order'           => 'DESC',
        'meta_query'      => array(
            array(
                'key' => 'date',
                'type' => 'NUMERIC', // MySQL needs to treat date meta values as numbers
                'value' => current_time( 'Ymd' ), // Today in ACF datetime format
                'compare' => '>=', // Greater than or equal to value
            ),
        ),
    )
);