I agree w/ the first post. It really depends on how big they are however. Also, separate the large ones and put them in a heated area w/ some healthy gutloads and water crystals and you will have thousands in several months.
The generally a dubia that's the same length as a large cricket is two or three times that cricket worth of food. So if you feed 6 inch long crickets, 2 or 3 inch long dubia are about the same. It's really up to you to decide the 2 or 3 part.