If you assume that an average adult needs at least 2.5 feet of table perimeter, that means that for 8 persons you need a total of around 20 feet. If that is the circumference of the table, its diameter would be 20/3.1415 = 6.4 feet, or 6 ft 4 in (approx. 195 cm).

If your table meets or exceeds these figures, the company of 8 will be reasonably comfortable, provided there is additional space for seating them around the table.

Obviously, it depends on how big the round table is. A bottle is round. If it is the size of a bottle, then no. Some mountains are round. If it is the size of a mountain, then yes.

I suppose you need a big enough table and comfortable chairs for that.

Yes - If its wide enough.