When using Seating Charts add-on, handling number of the available tickets is a bit different than usual. Normally, you would create your ticket type and enter a number of available tickets for that ticket type to the Quantity filed. And that is okay and should be done like that for all the ticket types that will be assigned to the standing areas as standing area does not have assigned seats.
However, if you plan on having assigned seats, Quantity field in ticket type does not affect the number of the seats you can create and assign. In other words, you are defining the number of available tickets by creating an assigned seating groups and as long as there are seats which tickets were not purchased for yet, this ticket type will be available regardless of the quantity set within Ticket Types. So, it is advisable to pay close attention on the number of the seats when creating seating groups as that will resemble the number of available tickets.
Also, the exact same scenario applies to the tables as seats for the tables should also be assigned in order for a customer to be able to purchase the ticket for it.