is walking 20,000 steps a day too much for a 41 year old male?dddddddddddddddddddddddd?

That is somewhere around 10 miles - maybe a little more. I don't think it's going to kill you but you might be pretty beat up after all that walking.

I walk 4-6 miles a day and that's plenty for me.

depends on your system, if you get too tired i would quit

More than you need to do - but as long as it doesn't over-tire you too much, nothing wrong.  

What kind of walking?  A BRISK walk of 45 minutes is enough to raise the heartbeat for maximum benefit.  And - my doc recommends taking at least 1 day off a week - preferably 1 day of rest after each 3 or 4 days of exertion.

No guarantees, of course . . . . I've been taking a brisk walk of about an hour most mornings since I was 18. . . . but no way to know if it does any good as I'm only 76.