I think you mean they fill labor demand or that they diminish the supply of jobs by providing labor. This however incorrectly assumes that the demand for labor is fixed. That demand is affected by supply + cost of labor and demand for goods and services. Immigrants consumer goods and pay of services so more immigrants means more aggregate consumer demand, which leads to higher demand for labor. In the end immigrants result in a net labor demand increase due to consumption. Immigrants no matter how frugal still get haircuts, buy groceries, see doctors, pay for tax help, call plumbers, by pants, go to bars, buy used cars etc.
I think you mean they fill labor demand or that they diminish the supply of jobs by providing labor. This however incorrectly assumes that the demand for labor is fixed. That demand is affected by supply + cost of labor and demand for goods and services. Immigrants consumer goods and pay of services so more immigrants means more aggregate consumer demand, which leads to higher demand for labor. In the end immigrants result in a net labor demand increase due to consumption. Immigrants no matter how frugal still get haircuts, buy groceries, see doctors, pay for tax help, call plumbers, by pants, go to bars, buy used cars etc.