I clicked the link you provided and found zero discussion of illegals or the taxes they pay or the govt. services they use.
"But immigrants also pay taxes. The present value of lifetime earnings for the typical immigrant man is $380,000. With 7.6 million working immigrants (both men and women), total earnings of immigrants are at most $2.9 trillion, of which about 40 percent, or $1.2 trillion, are paid in taxes of all forms. Because 3 percent of total revenues are allocated to cash welfare benefits, immigrants pay about $36 billion ($1.2 trillion times .03) in taxes to fund welfare programs. Comparing the $36 billion that immigrants contribute to welfare to the $56 billion they consume, immigrants consume $20 billion more over their lifetimes than they contribute. Thus, the welfare system causes U.S. natives to lose about $1.1 billion per year (in present value terms). Subtracting this $1.1 billion from the $5 billion annual increase in national income, the United States benefits from immigration, but the economic gains are small. "
I used this as a conservative example, assuming Illegals pay less the legal, and use equivelent services.