Depends on the size of your average players. A 48" round table should comfortably fit six. I used to have a 42" round table that comfortably fit six <200 lb players, but I don't know if you can "get away" with an even smaller table.
I built a 4ft octagon table. Before I finished it, I actually thought 8 people would sit comfortable. It fits 6 nicely, and can squeeze 7 if you use chairs with no arms and everyone is cool with knocking elbows occasionally.
Thanks. Unfortunately I sold the table to another member earlier this year. I kept my Broken Bell insert though. Needed to make room for another hobby. I'm back using the dining room table and a PCF topper for now.