Means that coffee is always kept on the table and it is there now.
I don't agree that this would be the case for every situation, M. Don't you think that, "Coffee is kept on the table" might be employed as an admonishment to an employee who has put it away in, say, a cupboard?
2)Coffee has been kept on the table.
Means that coffee was kept on the table for a period of time in the past, but may not be there now.
That could be the present perfect of experience; "in our past as a restaurant, we have kept coffee on the table [it has been our experience to ...]. To reflect this in speech, I'd say that the "has" may well receive grater stress,
"Coffee haaas been kept on the table" ,
though it wouldn't have to have.
But to my mind, there are other possibilities.
A: Do you keep your coffee on the table? What's your policy regarding that?
B: Well, as a rule, coffee has been kept on the table.
The intonation here, illustrating that this is an ongoing thing, would be more flat, more even. I think that this example might illustrate the difference that Ssthrn was getting at.