Having Lupus doesn't always mean you'll have a shorter lifespan than people without Lupus.
As long as you get treated for Lupus you can live a full life expectancy and live for 40 years after diagnoses depending on your age at time of the Lupus diagnoses.
If you leave Lupus untreated it can be fatal much sooner as in maybe a year or two or even less.
When Lupus is left untreated it can lead to organ damage and failure as well as kidney disease and kidney problems, pancreatitis, pleurisy, vasculitis, pericarditis, and cancer.
So as long as you get treated for Lupus you can live a nice long life and not have a premature death as a result.
Lupus is not always a death sentence as long as you get treated for Lupus in a timely manner.