In all fairness, as someone who is half Polish, wages in Poland are simply quite poor. Obviously this seems shocking, but what about all the big companies that outsource work to China and whathave you? They are paid far less than the people in Poland.
Additionally, the cost of living is also far cheaper in Poland than in other countries. For instance the average rent for a city centre apartment today is 2,100 zl (this would be quite a bit lower in 2014). If you're renting in the city centre you'd be expected to have some kind of flat share, be living with a partner, or quite wealthy yourself.
With all of that said, the wage is quite poor. There's no good reason that CDPR should be paying their staff minimum wage, especially when they're clearly benefiting from the sales of their game across an international market. One would expect that CDPR should be able to give all of its employees a very healthy wage.