DiegoHG:
That would be, on the left side, IOREF, RESET. 3,3V, 5V, GND,GND, Vin.
Those pins can only be used for their specific purposes. They are not I/O pins.
Also, don't use pins 0 and 1 as they are used for Serial communication,
The analog pins A0 to A5 can also be used as digital I/O pins.
Post a link to the datasheet for the thermocouple amplifiers. I wonder if they can share some of their pins?
...R