I think this has been sort of discussed previously, adding that thread here Is there a case and connection method for ThingWorx-kafka connection? for additional information, which i'm afraid is not much. Looking forward to what Durgesh Patel finds with PM.
You need an agent/connector (can be stand alone Java application) which reads from the Kafka Queue and writes it to your Thing property. Alternatively agent code can be built as extension and that can be invoked using scheduler job. Java could be slower considering velocity of data Kafka can handle.
You can alternatively think of Python code, you have agent code available here GitHub - dpkp/kafka-python: Python client for Apache Kafka
Then you need to use Python extension (not sure whether it is available in Market Place) to invoke your Python code from scheduler.
I hope this helps.