Exposure value (EV) is not an amount of light and it also has nothing to do with ISO. It is simply a definition for relating camera settings which are equivalent to each other in terms of how much light they would let in, if there was the same amount of light available.
Setting your camera to f/1.0 and 1 second exposure is still called an EV of 0 even in complete darkness or in bright sunlight. Setting your camera to f/1.4 and 2 seconds exposure is still EV 0.
By telling someone that you are obtaining proper exposure by an EV of 0 and a certain ISO value, then and only then does the actual darkness or brightness of the scene come into play. In that case, changing the ISO will change the EV needed to obtain proper exposure for the same scene. And vice versa, changing the brightness of the scene will also change the EV needed to obtain proper exposure for the same ISO.
So you might ask why then does Canon present on their 6D product page a meaningless specification about sensitivity at -3 EV? EV doesn't mean luminance, but they are acting like it does.
The answer is that it is well-established practice among photographers to express luminance in terms of their camera settings using the EV terminology, by assuming that ISO 100 is used and that a nominally "correct" exposure is being obtained by the camera settings indicated by the specified EV. Since photographers probably communicate best when talking in terms of their camera settings, EV makes for an easy way to understand the level of available brightness for a photographer when this common practice is used.
Anytime exposure value is used to speak of the amount of available light, the assumption is that a CORRECT exposure will be obtained from that EV of aperture/shutter speed AND a sensor sensitivity of ISO 100.
5DIII, 5DII, 7D x5, 6D, T2i, T3, 1D X, 10-22mm, 16-35mm II, 18-55mm II, 18-135mm IS x2, 70-200mm f/2.8L II, 24mm f/1.4L II, 50mm f/1.4, 50mm 1/1.8 II x2, 85mm f/1.8 x2, 100mm f/2 x2, 135mm f/2L x2, 200mm f/2.8L II x2, 1.4X III, 2.0X II, 60mm f/2.8 Macro, etc. only had room to list a few Canon items