I have a German passport and use ESTA to enter the US, my wife has a regular visa
Can she use the ESTA line with me?
There is no ESTA line. Both you and your wife will need to use the "Visitors" line when entering the US.
If you have entered the US before on ESTA, then you may be able to use the US Citizen kiosks (it depends on the airport), however even if you are allowed use them then your wife will need to use the Visitor line as she is on a visa so you might as well use that line as well.