Sounds like a scam. Do not provide that site with any personal information, do not use a login service to connect to the site (Facebook login, Google login, VK login, etc.).

Firefox does not provide prizes for surveys. Websites can use popups and notification settings to make it seem like the notice was from Firefox.

This is a scam I have seen reported by some Firefox users every so often in last while.

This is 100% FAKE and was not a message from Mozilla or the Firefox web browser. Do not give them any personal information or send them any money by any means. Variations of this sort of scam has existed for a long time, not for Firefox users but in general.

Mozilla does not do any so called surveys with claims that you have won or will receive insert expensive prizes as the three main variations of this scam have been for a iPhone X, a $1000 gift card or a Samsung S8 or S9.

Mozilla has done surveys over the years by way of http://qsurvey.mozilla.com which is surveygizmo.com however no prizes are given.

Below images are examples of this Fake iPhone X for a $1 scam reported so far.