How strong is the super glue to the bike pedal holding to the screw hole?

The bike pedal is loose and btw, it's a treadmill machine.

Well considering the glue has to take a huge amount of weight and pressure from the rider, the BLUE substance has to be strong. Whether it would glue on to a treadmill machine is a different story. I say get loctite glue. The strong stuff.

Super glue is something like Crazy Glue. It is used to hold things in tension. That is, while pulling on the two glued parts. If you put it in shear, it will break just like you would tear a piece of paper. Just bad news. Never use instant glue on a bike. It's too dangerous.
Thread locking glue like Lock-Tite is just what it says. The blue stuff has the right amount of tension to hold until you use a hand tool to loosen the part.
I have never needed to use thread locker on bike pedals. I simply used a pedal wrench. I believe it's 15 mm. Pedals almost self tighten unless you pedal backward a lot.
If you're still having trouble, check out a bike shop. They will generally work with you and for a very reasonable cost. They can tell you if it's a bad part and maybe get a replacement.

You may be talking about the loctite super glue? Its generally blue in color and is put on screws and bolts to hold them better. It makes the part more reluctant to unscrew/unbolt, but with a wrench it should come loose.