The gauge will read 12 volts if you run 8 AAA batteries in series, but it won't start the engine.
If you have a charger, you should put the battery on it for a while, just to make sure it's fully charged. You need to clean the posts on the battery, and make sure the new clamps are tight. When you try and start it, if it doesn't crank over, and just clicks, turn the headlights on and see what happens to them when you try and start it. If they get real dim when you try to start it, the battery isn't charged. If they remain bright, try cleaning the terminals on the solenoid. If they go out, and stay out, double check the connections at both ends of the battery cables.