I wouldn't go for 'pure blood'. We don't know who his father is, and we might never know since his mum was a prostitute. But as far as it goes, yes, as mentioned in a chapter a few months back, Kenny was the older brother of a sister who ran off to become a prostitute, and got pregnant.
So yes, he is an Ackerman by his mother, like Mikasa is by her father.
Now what really comes to question is if Mikasa's strength is because she's an Ackerman, or other reasons, seeing as to how Levi and Kenny don't posses her super human strength and healing.
Thank you...now i have the clearer or better idea.. really thank you
wait what???so kenny is levi's uncle and levi is a pure blood ackerman??? id ont know if i got that right....so this story is getting more interesting for me...and now i wonder when is the next release of chapter????