The answer depends on where his wife and children lived and whether or not the taxpayer chooses to file a joint return. If his wife and children lived for more than six months at the home in the United States and she qualifies for EITC, he would qualify for EITC if he filed a joint return with his spouse. If his wife and children lived with him for more than six months outside the U.S., he would not qualify.
On average there are: 6 slices per small (8-10) pizza, 8 slices per 12 inch pizza (medium), 10 slices on a large (14-16) pizza and 12 slices on an extra-large pizza. You should confirm the number of slices before ordering because this will vary between pizza providers.
So for 50 people that is approximately 12 pizzas if nobody has eaten dinner yet. If the pizzas are only 14 inches then you would need 16. If you expect that people will be engaged and excited then you should have a few more. People eat more when they are having fun.