This depends on the policies of the casino. But majority do not permit their employees to gamble in their casinos since the employee has inside knowledge of how it works. However, the employee could still gamble in other markets.
Like all gambling games, luck plays an important role in poker, especially over time. However, poker is different from other forms of gambling. Unlike other games under the casino floor, poker is a game of skill and the best professionals in the world are paid for being the best players in the game.