Hi OOAJ,
Yes, when the Auctiva website is offline for weekly database maintenance, your listings will still be searchable on eBay, and your buyers will still be able to place bids on them. The scrolling gallery will remain running in your listings as well, but may be empty under certain circumstances.
Any additional questions? Please file a support request using the appropriate link on our help page: http://www.auctiva.com/free-auction-software-help/help.aspx
-Mike