Hi, if your accommodation is arranged and paid by your employer which is normally the case for all the expats, 1200USD is good to start with. If you are alone and cook yourself your month expenditure would be say 400-500USD depending upon you lifestyle.
Seychelles is nice place and people here are lovely and enjoy their life to fullest unlike other countries.
So if your offer is still open for job check for accommodation, air ticket , OT , other allowance from employer and grab the deal.