is dr. solomon margoline dead or alive??...what should we make out at the end?

yes he is dead, because he himself mentions that he might be a part of the astral world,where dead souls float because of some unfulfilled wish or desire. it all falls into place for him a few minutes after talking to raizel, and he finds coincidences like the fact that the body dragged out from the taxi looked very similar to him, that it could have been himself,the fact that he could not find his wallet, and most importantly, meeting raizel, because he knew that she was dead. but despite all these instances, the reader is left to make their own impression and conclusion.