Pi is pretty close to 3, but 3! is exactly 6.

"the reason we dont know what it is for sure is because the circumference is kind of hard to measure accurately, so we dont get an accurate number for pi"

We do know what it is, it's pi. We calculate it as the sum of a series or some such. The series is infinite so you can never finish the calculation. On the other hand you can get any desired degree of accuracy given enough time. The accuracy with which we can measure circles has nothing to do with it.

Pi is finite in the sense that it's less than 4. On the other hand pi, expressed as a decimal number is infinite- it has an infinite number of places of decimals. This is related to the issue of "squaring the circle" and has been proven to be true. Caboose17 is, therefore, talking out of his hat.