Die Linke gained more than 10.000 member this year alone so we are seeing a small gain in their popularity and polling around almost 6%. of course that is in large because there will be elections soon.
it is true that the DKP is a very small party at the moment. 50 years ago they had i think about 60.000 member. right now they are not gaining much influence, but they are very well read and active communists.
the only thing german communists can do is join the dkp and organize in unions and their workplaces as well as on the streets, with the guidance of the party.
Die Linke isn’t pro-israeln. They say they don’t want to send weapons in reagilns of war (which they will never have a say in) but they do say israel has a right to defend itself.