How long can a person live for with lupus?

Decades. Depending on severity and extent of disease, and how responsive you are to medication the disease can often go into remission. There are people with severe cases as with any other disease, bit treatment is helpful in a very high percent of cases.
Varies with severity. Lupus can vary from mild to severe. How you deal with the disease includes medical treatments, anti-inflammatory supplements such as omega 3 fatty acids, psychological support as with any chronic problem. Support groups of other lupuspatie ts can be helpful.