Einstein looks at least 2000 strength in that game, possibly stronger. I don't know why some of you guys are estimating 1400/1500 (show me the patzer moves he made.) He executed his attack with strong and fluid precision.
Im not really sure that you could assign a value to his play after one game, but he certainly played significantly better than a 1500. From my experience in USCF, players at 1500 and below are basically tactical and strategic beginners, and have merely gotten to the stage where they dont play completely terrible. This game showed Einstein was not a tactical beginner. Oppenheimer on the other hand ...
I know that Einstein used to discuss his theories with Emmanuel Lasker..!