How to add Qty in add to cart form on Product Listings Page in Magento 2
On this form just add below code
<input type="number" name="qty" id="qty" maxlength="12" value="<?php /* @escapeNotVerified */ echo '1' ?>" title="<?php /* @escapeNotVerified */ echo __('Qty') ?>" class="input-text qty" />
and check what is happen :)