What is the going rate for general office cleaning about 5,000 square feet and how long will it take to clean the office building?

First, this depends on the market you are working in because you have to factor in your competition, overhead, etc.

Next you need to determine how many people you can afford to work the site at once, and/or how much time you have to get the job done.

As an example, if one person can clean the space in 8 hours, then you have a basis for your estimate. If you only have four hours to clean the space, then you will need two staff people.

If the client requests work that requires more time, if the cleaning includes more detailed work like bathroom showers, kitchens, etc. -- all of these details need to be factored in, leaving this question very hard to answer.

Most people already know they need to add those things into the equation... Most of us are seeking a direct answer. Something to use as a base to build on.