I'm not sure what you mean. He should have been able to easily have filled 20,000 seats. If it's because of the pandemic or people wising up to this con man I can't say. The following is an actual quote from a president of the United States, "At his rally in Tulsa on Saturday, President Trump called coronavirus testing “a double-edged sword” and said he asked officials to conduct fewer coronavirus tests to keep case numbers down. After claiming the United States has tested 25 million people, Trump said: “When you do testing to that extent, you’re going to find more people, you’re going to find more cases. So I said to my people, ‘Slow the testing down, please!’
From The Washington Post