You have no critical reading skills. He posted that Democrats REDUCE THE DEFICIT. Nothing about spending cuts. The deficit is the shortfall between revenue and expenditures. There are lots of ways of reducing the deficit that don't include cutting spending:
1. Obama's job creation and increases to wages for lower income workers resulted in more than 5 million people coming off the food stamp program. That's a huge cost saving for that program, which would impact the deficit. There were similar savings under every income assistance program the government runs as more and more people found work, and no longer qualified for assistance.
2. The Affordable Care Act made changes to Medicare and Medicaid to reduce the costs of these programs overall, and the bill made essential changes to health care structures which both stabilized the programs, and reduced the costs. Trump cut the taxes which paid for the ACA thus increasing the deficit.
3. With corporations having record profits under Democratic Presidents, and the stock markets reaching record heights, both corporate and personal income tax revenues rose accordingly, and the deficit is reduced.
The economy is a huge and complex system and there are many ways of impacting both costs and revenues. Republicans always dumb down their economic points to a slogan that says "Republicans are better for the economy than Democrats". But they really are not better for business. Not by any economic measure: job creation, stock market growth, unemployment, wages. They just lie and say they are.