It seems form various news reports that Netanyahu made a proposal offering Gantz an emergency unity government in one of two ways:
1. a 6 month government led by him, with the various positions divided up equally between them after which they will return to the exact spot we are in today regarding formulating a government and possible elections
2. a 4 year unity government in which Netanyahu serves out the first two years and then Gantz serves the final 2 years. They each would commit to not topple the other during the 2 year terms. Roles would be divided equally.

Gantz has not said yes or no, but it seems he thinks Netanyahu is pulling a fast one on him and is therefore hesitating. he wants commitments form Netanyahu and claims Netanyahu has not set an actual meeting to discuss it with him, but is only making statements to the press to make himself appear as having offered it. Also, Gantz is suspicious that Netanyahu is ordering these draconian restrictions for the purpose of delaying his court case - after all was announced last night, only at 1am when the press was no longer in full reporting mode did they slip in the closure of the courts except for emergency situations, thus strengthening Gantz's suspicions.

Whatever the truth is, Gantz does not really have much of a choice. Unless Netanyahu totally blows it with the Corona situation, Gantz is going to be decimated by it. I don't think anyone thinks Gantz would do a better job. If Gantz puts together a minority government and does a fabulous job that is his only other chance of coming out ahead, but that is a very risky gamble. The minority government might not come to be, and even if it does, it very well may not function well enough to give Gantz a hold on any future in government.

Gantz's best chance is a deal with Netanyahu now that puts him in the driver's seat in 2 years. It is a risk because who knows what will be in two years and nobody knows if Netanyahu will step down as agreed to, but it is really Gantz's only realistic choice. He would be a fool to not take it. He already missed from the deal he didn't take a year ago which would have had him as prime minister today.