You have no way to know unless you can ask someone who has gotten income for the facility already.
Basically, facility income depends on a number of factors (all listed in the rules), some of which are intentionally unknown and some of which are random. The facility needs to be powered, and you can maximize the income by assigning someone with a high Trading skill as operator.
'Max' income is hard to judge, and depends on the type of facility. For taverns/hotels (generally the most common income facilities), 40K income is considered very good. For personal residences you're unlikely to get more than a few thousand credits a month.