You won't receive money for winning, unless you continue the plot.
Last opponent is Count (Monsters deck, Eredin card). First opponent is Bernard Tulle (Northern Kingdoms deck, Foltest card), second is Sasha (Nilfgaardian Empire deck, Emhyr var Emreis card) and automatically another opponent Finneas (Scoia'tael deck, Francesca Findabair card) - after the battle with this opponent a fist fight for life or death will start. 1000 crowns and a strong enough deck will be required to enter the tournament. High Stakes - Most prestigious tournament in which you will have to defeat four opponents in a row to complete it successfully. Then the inn owner in Farcorners (Nilfgaard deck, Menno Coehoorn card) or available at this point Oliver in Novigrad's inn (Monsters deck, Tibor Eggebracht card). First win with Stjepan in the inn in Oxenfurt (Nilfgaard deck, Yennefer card). You must win with three opponents in different places. Gwent: Playing Inkeeps - continuation of the previous quest with Gwent players in Novigrad. For completing the quest you will also receive commander card Francesca Findabair, the most beautiful woman in the world. Last opponent is elven merchant in Farcorners (Scoia'tael deck, Cirilla card). Your next opponent is Dijkstra - you will be able to play with him after advancing in the storyline (Northern Kingdoms deck, Esterad Thyssen card). After winning with Vivaldi (Scoia'tael deck, Vesemir card) go to Marquise Serenity (Nilfgaard deck, Moorvran Voorhis card ). Gwent: Big City Players - you receive this quest after talking with Vimme Vivaldi in Novigrad. Once you defeat any of them, you will unlock access to playing with Hadek in Midcopse (Northern Kingdoms deck, Vernon Roche card). After winning with Baron (Northern Kingdoms deck, Sigismund Dijkstra card), win with the boatbuilder in Oreton (Nilfgaard deck, Letho card) and fortune teller in Benek (Monsters deck, Weavess crone card). You start it with a game with Bloody Baron and you have three more enemies to defeat in villages. It's the first phase of the tournament games. Gwent: Velen Players - players from northern part of Velen. When you no longer are rewarded with a card after the game, then it means that you have all non-unique cards. To collect all of them, you must complete all quests related to the card game and defeat most (not all) "standard" opponents (innkeepers, merchants).
The number of cards, including the repeated ones, is limited. You can have more than one piece of some cards - in this quest you must have every card, especially the unique ones.
It's about collecting all possible cards. Gwent: Collect 'Em All - first quest that companies you for most of the game. In addition to standard Gwent games against merchants, there are some tournament games with stronger opponents in which you can win unique cards.