Would it still be okay to eat a can of corn opened on Thanksgiving Day and put the leftover in fridge and today is six days later?

Corn in the can usually has a lot of salt. Even so, it would depend on the average temperature inside the refrigerator and whether the corn was exposed to airborne bacteria after the can was opened. The problem is that the corn is eventually going to ferment (as in making moonshine whiskey) from the water and sugar in it. If it smells or tastes sour, it's best to toss it out, although it probably would not make you seriously ill to eat it.