I do not drink coffee and am not a fan of this drink, and I cannot say anything about its usefulness. But according to general statements, coffee is a good legal stimulant.
As for patience in poker, you should approach the game in a calm neutral state, take your time and be interested in the very process of playing poker. When there is no patience, it means that you are not interested in the game, you are more interested in the profits and winnings from this game. Try to play poker as a hobby, take an interest in the process itself, read the literature on the game, do not expect profit, but expect positive emotions from new skills. And over time, when you pump your skill and patience enough, you will gain profit and satisfaction from the well-deserved profit.
In general, you can read special literature on the psychology of the game of poker, now there is a lot of it on different resources, and I am sure that you will find a lot of useful information for yourself.