Translated quotes of what he said in a secretly filmed conversation(to be released as part of a documentary later in the evening):

"We can still shoot them [migrants] afterwards. That's not an issue at all. Or gas them, or whatever you want."

"The worse Germany is, the better it is for the AfD. Of course, that sucks, for our children too. (...) But that will probably keep us going."

German article with quotes here

English article