This is perhaps the most valuable piece of information on this blog. The attached link will open a spreadsheet that details out the various financial components of a restaurant - The Initial Investment, The Operating Costs and Staffing Costs. I have used a standard 1000-1500 sft (about a 40 seater) Indian restaurant serving food at reasonable prices (Rs. 100-150 per person per meal) as an example. You can play around with the data to suit your specific business idea.
Disclaimer: Please note that the numbers are indicative and based on information I know. So kindly validate the figures for yourself. The spreadsheet needs to be used more as a template than as an actual financial planning document.