Make a killing off

In Band of Brothers WWII miniseries one of the guys said:

"There's gonna be good times. When we get home, I mean. First thing I'm gonna do is get my job back at the cab company in Frisco. Make a killing off all those sailors coming home, you know?"

What is "make a killing off", what does it mean?

It means to make a lot of money.

He sees business increasing due to all those sailors coming home and he wants to to drive his cab overtime to take advantage of the increased business.