Help - in limbo regarding joining

guys, need your views on this. one of my close friend's notice period coming to end wednesday and joining other firm on thursday. also there's a round ongoing with global ecomm major, which supposed to close by monday max with Hr discussion & sharing docs on same day but they're saying it may take them a week or more release offer letter and then she can join this would mean either delaying the joining in currently offer holding org or to let them go and sit idle in the period till the new org releases offer letter but again look at the gamble involved. low but still not 0 chances that later there might be some issue or related which may delay the joining further or even if hiring freeze comes in may result in hold of offer letter. what would you do in such a situation? joining offer holding org and then jump to new once they release? (would mean quitting in couple of weeks or so) or take the risk and wait for a week or so (ETA uncertain) till they new firm releases the offer?