I have been searching the interwebs trying to find an extractor for pfsense for graylog and have been coming up short. So I took matters into my own hands and decided to do this from scratch.
I have built the extractor using the raw filter log format located on the pfsense documentation
https://docs.netgate.com/pfsense/en/latest/monitoring/logs/raw-filter-format.html?highlight=raw%20filter%20format
If you want to reap the fruits on my labor you can find the extractor on my github. If you find any issues with it, just open an issue.