shopUpz Inventory app provides you an easy way to track and monitor your quantities between Etsy and Shopify stores. Inside the "Inventory" tab you can view all of your Etsy and Shopify SKUs side by side. By default you will view all of your existing SKUs on Etsy and Shopify. That said, if you have just created a new SKUs on Etsy or on Shopify then click on the "Reload New Listings" (view image below) in order to display the new SKUs on the inventory page so you can view it.
Note - this operation is not related to quantity updates only for new SKUs/listings creation.
Reload new listings operation may take few minutes and the following screen will be displayed
Another great way to track after your quantities and make sure that your stock is aligned between Etsy and Shopify is to export quantities
Happy sales :)