From their website:
Seating capacity, Upper Church (approximate): 3,500 persons
Total capacity, Upper Church (approximate): 6,000 persons
It is the largest Catholic church in the United States, the eighth largest religious structure in the world, and the tallest building in Washington, D.C..
Thanks BBG!
That’s big! But you can be certain it won’t be close to being big enough. I suppose it will allow many to pass through to pay their respects.