When you set your Etsy store to Vacation Mode, it'll remain synced to Printful. Your Etsy products will also remain synced, but you won't be able to add new products from Printful.
However, orders will not import while your store is set to Vacation Mode. During that time you'll need to manually submit any store orders in your Printful Dashboard.
When you turn off Vacation Mode, orders will import from Etsy again!