Basically, Konami has stated that depending on the number of Retweets they get, they’ll reveal a certain amount of cards after the episode.

Edit: A correction.

https://twitter.com/YuGiOh_OCG_INFO/status/639725000736444417/photo/1

Approximately 999 or less: 1 card
Approximately 1000 or more: 2 cards
Approximately 2000 or more: 3 cards
Approximately 5000 or more: 4 cards

Edit:

This isn’t the Tweet to Retweet, there’s a particular Tweet they want retweeted on Sunday, that mentions 「デュエル！」 and it’ll be on @yugioh_anime