Pesquisei regras no Pokerlistings.com e o site veio com uma situação que reflete a pergunta postulada pelo Augusto, sobre o sujeito que aposta pouco e fica de fora das demais rodadas de apostas. Segundo essa regra, as 5 cartas valem para ele (que pagou por menos cartas), assim como os demais.
Table Stakes in Pot-Limit and No-Limit
Table stakes are used in almost all poker games today. It provides protection so that a player can play with any amount he has in front of him. This means that if two players are involved in a hand and one has $100 and the other has $50, the player with $100 can bet, at the most, $50 (consequently, he can only lose $50 on the hand).
Example
It is a No-Limit game and three players (players A, B, and C) are involved in a hand. Player A has $300, player B has $200 and player C has $100. Player C goes all-in and bets $100, player B calls and must put in $100 out of his $200, player A chooses to raise all-in and bets $300 and player B decides to call all-in with his last $100.
In a situation like this, a side pot is created. The main pot contains what player C can win ($100 from C + $100 from B + $100 from A = $300) and the side pot contains (B's last $100 + $100 from A = $200). As such, player A has to take $100 back.
Once all the cards are dealt, player C wins the main pot ($300) if he holds the best hand. Player A or player B will win the side pot ($200), depending on which of them has the best hand. If player A or B hold the best hand, that player will then win both the side pot and the main pot ($300 + $200 = $500).