It will not natively support an 8 port, no.  My understanding from the
ESP reference is that port 0 is the master, and ports 1..7 the slaves.
Only a master port can run in 16550 emulation mode, which is how the
current ESP support works -- though now that I look, that may not be 
the case.

I've never heard of anything above a 2 port mentioned, and I've never
seen one of those.  I can't tell from a browse of the reference how the
board, on interrupt, tells you which port to service -- does polling all
the ports on interrupt make any sense?

-john