The provision of data to CYSTAT is mandatory.

Specifically, according to Article 13 (2) of the Official Statistics Law of 2021, the provision of data for statistical purposes by any person is mandatory, to the extent that this data is absolutely necessary for the production of official statistics.
Судя по их сайту — да, вы обязаны ответить
https://www.cystat.gov.cy/en/StaticPage?id=1146