https://secure.osfa.illinois.edu/NPC/NPC.asp is UIUC’s net price calculator.
For a dependent IL resident student CS major with married parents earning $60,999, it estimates at net price of $27,466 after $8,544 grants subtracted from $36,010 list price, according to https://secure.osfa.illinois.edu/NPC/Results.asp?studentRes=Yes&BudgetCode=URCO&Major=Computer+Science&fafsadt=Yes&Parentmaritalstatus=Married%2Fremarried&NumberInfamily=3&NumberIncollege=1&ParentIncome=60999&incomefrom=Both+parents&ParentIncometax=3000&Parentassets=0&StudentIncome=0&StudentIncometax=0&Studentassets=0 . Since the non-tuition part of the list price is $15,008, the promise does not appear to be reflected in the net price calculator.
Note that even free tuition may not make UIUC affordable to many lower income IL residents, since UIUC is in a less populated area that requires many students to live there at higher cost than commuting from home would cost.