My sister in law has a multiple tourist visa right now, she got it through her previous work. Now she wanted to apply an h2b visa to work right here in orlando, will it affect her b2 status. Does she have to give up one visa to another.

It depends.. the consulate won't cancel visitor's visa but immigration officer at the port may do that...
The best choice is apply for H-2B at the US consulate in her home country..