On an SLR, since the image is transmitted by the attached lens regardless of whether you use the optical viewfinder or live view, both live view and the optical viewfinder will show what the sensor sees, including the effect of any filters or modifiers attached to the lens. Indeed, live view is a feed directly from the sensor.
Not all viewfinders offer 100% coverage of the sensor, however. The exact coverage will be listed in the camera's technical specifications, so if your camera shows less than 100% coverage you will need to check for objects intruding on the very edges of the frame that may not be visible when you frame the shot using the viewfinder. There may also be vignetting which will not be visible through the viewfinder but which is evident in live view and the final photograph.