(I am considering only real matrices)
Does only hold that if the area of all Gershgorin Circles is positiv $\Rightarrow$ the Matrix is positiv definit (trivial)
or does also follow the vice versa
the Matrix is positiv definit $\Rightarrow$ the area of all Gershgorin Circles is positiv
The reverse direction does not hold: $$ A=\pmatrix{ 1 & 2\\ 2 & 10} $$ is positive definite, but the Gershgorin circle for the first row contains numbers with negative real part.