if custom field is older than date next week

I’m trying to find a way to query on single.php if a post custom field (a date) is greater than a date 7 days in the future.

<?php
$date1 = get_post_meta($post->ID, '_timestamp', true);
$date2 = date('YmdHi', strtotime($date .' +7 day'));
if ( $date1 > $date2 ) { ?>

The idea is to be able to filter those posts coming up in the new 7 days and those that are not. Custom field _timestamp outputs the date as YmdHi, so I’ve done the same with the date function.

Something doesn’t seem to be right though, and I’d appreciate any help with this.