In theory, pi has infinite digits. You could publish a book of a trillion digits of pi, and you have barely scratched the surface: in fact you published a precisely 0.00000% of all digits of pi.
In practice, you "only" need ~42 digits of pi to draw a circle spanning the entire known universe (diameter of 8.8 * 10^26 m) and it will deviate from the ideal circle by less than the size of a proton (0.8 * 10^−15 m).
Having a theoretically infinite precision does not mean that it makes a measurable difference.
Every number has infinite digits or can be made to have infinite digits for a given representation, but that's not the same as a number having an infinite amount of information. PI represents a finite amount of information, as opposed to say a number like Chaitin's constant which represents an infinite and irreducible amount of information:
In practice, you "only" need ~42 digits of pi to draw a circle spanning the entire known universe (diameter of 8.8 * 10^26 m) and it will deviate from the ideal circle by less than the size of a proton (0.8 * 10^−15 m).
Having a theoretically infinite precision does not mean that it makes a measurable difference.