Let us consider a positive charge placed at a distance $x$ on left outside the cube of side $a$. The electric fields are entering the cube from left and exiting from the right. Will the flux in the cube be zero or will it have a finite value?

The electric field varies inversely with distance as $E$ proportional to $1/r^2$. Since area is same, would the flux through the left side be greater than flux through right?

$$E.A=A.kq/x^2$$
$$E'.A=A.kq/(x+a)^2$$