Percentage signs have special meaning in crontab and need to be escaped, like so:
* * * * * php /Applications/AMPPS/www/laravel/artisan check-banners $(date +\%X)
Also, I'm not sure, but you may need to wrap the +%X argument in quotes as well:
* * * * * php /Applications/AMPPS/www/laravel/artisan check-banners $(date "+\%X")