Only 4 more years.
The absolute max that can be served is 1 day short of 10 years and can only happen if you take over, unelected, from the sitting president and serve less than two years as the non elected president. You can then serve 2 full terms if elected in your own right.
The number of years a president can serve in the White House is spelled out in the 22nd Amendment to the U.S. Constitution, which states "no person shall be elected to the office of the President more than twice." However, if an individual becomes president through the order of succession, that is by taking office after the death, resignation, or ousting of the previous president, they are allowed to serve an additional two years."