I have read online that in the world to come each person will merit 310 planets . Is that true ?
Correct. The Talmud (Sanhedrin 100a) writes that there will be time that Hashem will give 310 ten worlds to each tzaddik (righteous person). This is based on the verse ( Mishlei 8-21 “To bestow on my beloved substance (yesh) and I will fill their storehouses”. The word “yesh” has a numerical value of 310, hence the verse is read to bestow on my beloved 310”. The Talmud does not say that it will be for each person, rather for each person deemed to be righteous in Hashem’s eyes.