Is Zeex partnership with amazon and xbox confirmed or that is still unknown for sure?
Zeek, our sister company, along with countless other are able to sell gift cards through our protocol. And yes Amazon and Xbox are one the over 350 retailers that Zeek currently works with.
Zeex.meI think everyone is focusing on Amazon and Xbox, but what we should be really talking about is the fact that you have 350 retailers in the mix and that is an impressive number. Is there a need for more in this early stages of the project?
You can preview most of the brands and retailers that will be available to Zeex at our our sister site
https://www.zeek.me/gb/buy-gift-vouchers/ 
As for a need for more retailers, we have many interested parties and will let the community know when we are launching them.
And the number could go up rapidly if the project does good once it hits the exchange. Is there any limit to how many retailers you can handle or does something like that not exist in your line of work?
The platform will be able to handle a huge amount of retailers there should be no scaling issues.
To expand a bit on the scaling issues, we had a question recently regarding volume and tps limit on the Ethereum network. We explained that even at massive volume the TPS limit will not be a problem for us because the vast majority of transactions happen off-chain. Take the Starbucks example. If you know you buy coffee there every morning, you're not going to buy a $5 voucher, you'll buy $50 or $100 at a time. Then, you'll use the voucher in-store to make small purchases until it's empty. This is much more efficient.
Great explenation, and that really makes more sense, in a way to make it like a debit card. The only problem is that you will have to constantly check ballances of numerous vouchers that you have in your possesion.