Some confusion has come up about claiming PokéCoins in the new Gym system. In the old system there was a button in the Shop that allowed for Trainers to claim their hard-earned Coins and Stardust, but this is no more. As a quality-of-life improvement, PokéCoins and Stardust are awarded automatically. Twenty Stardust is awarded when Trainers feed a defender a Berry. Coins are awarded when a defender returns to its Trainer. But it's the Coins that are drawing confusion, and a bit of backlash.
Every hour in a Gym a defender will acquire a PokéCoin. If a Pokémon is defeated before the end of the hour a Coin will not be awarded. In the old system, 10 PokéCoins were awarded per Gym held at the time of collection. In both systems, a 100 Coin limit per day (and, therefore, 700 per week) is / was imposed. (It is also worth mentioning that a Trainer can only hold 20 Gyms at a time. Clearly, this limit was put into place to balance spoofers and their unfair advantage.)
Every hour in a Gym a defender will acquire a PokéCoin. If a Pokémon is defeated before the end of the hour a Coin will not be awarded. In the old system, 10 PokéCoins were awarded per Gym held at the time of collection. In both systems, a 100 Coin limit per day (and, therefore, 700 per week) is / was imposed. (It is also worth mentioning that a Trainer can only hold 20 Gyms at a time. Clearly, this limit was put into place to balance spoofers and their unfair advantage.)
SOURCES: GO Hub and Trainer Tips