Hi Vasileia, this is an interesting question considering the importance of Costa Rica as a high-quality coffee producer.
According to ICAFE, the Costa Rican Coffee Institute, coffee production has different roles. The only data they provide for individuals refers to coffee producers, which they define as "a physical or enterprise individual that has the right to exploit a coffee plantation by any legitimate means, and is the person who delivers the coffee fruit to the coffee processor."
The most recent data point I found refers to approximately 27,393 farmers working in coffee production in 2021, according to ICAFE in its report "Informe sobre la Actividad Cafetalera de Costa Rica," published in November 2021.
This number doesn't mean much without context. According to the same report, the number of coffee farmers has dropped 23,238 during the past ten years, considering that in 2011 Costa Rica had more than 50,000 people working in coffee plantations.
In the past ten years, many factors have played against coffee producers, mainly climate change and commodity pricing, which have pushed workers away from coffee and into more lucrative opportunities. Bear in mind that many producers come from other countries too. Although these numbers refer to people working in Costa Rica coffee plantations, that doesn't exclude other Centroamericans that moved to Costa Rica during harvesting seasons.