Really depends on the country. Denmark lost less than a hundred Jews out of a few thousand. Poland lost 90%

On average across Europe about 65% chance of death.

Blend in? Might help for a few weeks, more than enough time to escape to Britain but you would have to plan in advance, I'm taking years before the nazis invasion in the first place. One of the first things the Germans did was find census data.

I suppose If you were very wealthy and knew what was going to happen you could easily survive as long as you got out as soon as possible.