The Karta Polaka does not by itself give you permanent residence or citizenship, but it makes both much easier.
Permanent residence
If you hold a valid Karta Polaka and want to settle in Poland permanently, you can apply for a permanent residence permit. The national visa for settlement is free for Karta holders.
Settlement allowance
Currently, a person who applies for permanent residence on the basis of the Karta can receive a cash allowance towards living costs, paid for up to 9 months. The draft amendment would make it a one-off payment by the voivode.
Citizenship
After at least one year of continuous residence in Poland on a permanent residence permit granted in connection with the Karta Polaka, you can apply to the voivode to be recognised as a Polish citizen. You must confirm your knowledge of Polish with an official document, such as a state exam certificate or a Polish school certificate.
The other route is a grant of citizenship by the President, which has no minimum residence period.
Source: powroty.gov.pl (in Polish). Check the current requirements with the voivodeship office before applying.