I think ESO is close.
I'm going to say 1650 based on the following irrelevant facts
New ground for Featherstone fans (unless they also support someone like dirty Leeds) and they are doing well so perhaps a healthy away following. However, it's Easter so many people may be away on holiday.
Away fans do swell the crowd but it's home support that needs to be increased.
I think that the club has tried to put a good package together and I have heard a mention on Radio Sheffield plus there is a voucher in the Star tonight in colour too!
I have no idea what the reaction will be from the Sheffield public for those who aren't already Eagles followers but to be brutally honest if there are any Eagles fans who consider themselves supporters but who can't be arsed to turn up on Sunday then I'd say don't bother coming again.