Bibi will win by a slim number and have to get a splinter party to join with to rule. The polls showing him behind are iffy as political polls in Israel have been unreliable in the past. Israelis are not likely want to face a nuclear armed Iran with BiBi’s opponent in charge.
He will have to get many splinter parties in his coalition to rule (see my post #16 in this thread). The current polls show Likud at between 22-24 seats; even if he does much better than that, he needs 61 for a majority.