Keynesian people say that if you expand money supply (central bank quantitative easing), you will stimulate aggregate demand and thus increase GDP. This worked good in the great depression of 1929, however it didn’t some years ago. The reason is the rational expectations of economic agents (i.e. consumers, companies, etc) that prevent that even with a higher money available the economy won’t run good creating the famous “money tramp” (don’t know the exact name in english), so the aggregate demand stays low and crisis continues present.
Monetarists say that you can increase GDP with more money available, however this does not true in the long run, maybe in the short run only. Here starts the discussion of what are nominal variables and what are real variables. Money is a nominal variable and production (GDP) is a real one, nominal variables cannot affect real variables so easy and cannot persist in the long run.
Hope this helps.