I'm sure it would, the loss of 7 million workers would hurt the economy, when you consider that they are doing jobs Most people wouldn't do, and that they make up large parts of some industries.Not all of those 11 million are in the labor force. The labor force is about 155 million and illegal immigrants are estimated to be about 5% of it. So this would not be a very large portion of it and probably would not tank the economy.
The problem with Trump's plan is that it would require extraordinary and draconian measures to carry out.