If it is seized in the knuckle, there are a couple of approaches to get it out.
Looking at what you have tried at this point and hasnt worked, the only option I see is to remove the knuckle and take into a machine shop to be pressed out. You dont want to try anything else with air hammers and such as it can distort or otherwise ruin the knuckle.
if you havent yet, place the axle shaft nut on the axle shaft and strike with a hammer so that axle is loose from the hub. Remove tie-rod or drag link from knuckle. Remove upper and lower ball joint nuts. strike the steering knuckle with a brass hammer near the upper and lower ball joints to loosen. Remove knuckle.
Once bearing has been pressed out, inspect inside of knuckle where bearing goes for bad scoring or other defects. if severe, replace the knuckle, otherwise new bearing could sieze up.