Pspice: parametric gain of dependant source
PSpice's syntax for in-line equations is the following if you want to multiply a voltage by a coefficient:

E1 1 0 Value = { V(2,3)*4 } ; the voltage source delivers V(2,3) multiplied by 4

G1 2 0 Value = { I(V1)*5 } ; the devices sources the current flowing in V1 times 5

If you want to manipulate the current flowing through the source, you will have to add in series with it a dummy 0-V source and use it to measure the current and multiply (for instance) by a coefficient:

E1 node1 node2 Value = { I(V1)*V(2,0) }

Keep in mind that the current in the measurement source (or in any component) is positive when leaving the device by its negative pin.