A dropped connection does not cancel a bet that the studio has already accepted. The round plays out without the player, and the result is settled as usual, so a winning hand is paid and a losing one is lost. In games that need decisions, such as blackjack, the rules set a default action for a player who does not respond in time. The help panel lists that default, and it is worth knowing before the first hand.
The video reaches the player a few seconds after it happens in the studio, and the delay grows on a slow connection or a crowded network. Betting windows are timed from the studio clock, so a bet placed at the last visible second can arrive after the window has closed and be rejected. Lowering the stream quality in the game settings usually shortens the delay, and a wired connection helps more than any option in the game itself.