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