"Paid" is not really the right term. Yes, there is a reward for simple participation, which tends to be higher for new members. If you go to https://giffgaff.com/profile/payback some time after the second week of January you'll probably find you've earned a pound or two yourself, to be accumulated and paid out in June. But it's not a contract of employment.
It's also awarded in a selective manner. After the initial first posts, payback for simple participation is minimal. Regular participants will not have earned anything significant from posting in this thread. Those who post only in the social areas are likely to get little more than a partial subsidy of their network charges. The main payments are reserved for those that provide the best answers to problems in https://community.giffgaff.com/t/help-and-support and for suggesting improvements to giffgaff, whether that be in the web pages, highlighting problems or making suggestions about how giffgaff might work in the future.
However, divide it by the number of hours you've spend online and you'll find it's a lot less than the national minimum wage. HMRC treats it exactly the same as money earned from a hobby. We could all earn more collecting glasses down at the pub. But there's more satisfaction in posting here and, usually, helping people to get the best out of giffgaff.
It's a pity you weren't around a month earlier.