Vayikra 23:33-43. How is Sukkot kept today? Is this mitzvot affected because it says, when you have gathered the produce of the land (Israel?)and a great number of Jews are in diaspora?

Shalom, Thank you for your question. The festival of Succot is a still kept today by Jews all over the world. Even though the essence of the festival, as mentioned in the Torah, involves going to Jerusalem and Temple worship, which we unfortunately cannot perform today, the other parts of the festival are still kept. We build Succot – or "booths" – which are temporary houses, with leaves for the roof, which we live in for the week of the festival. We also take four species (palm, myrtle, willow and citroen) and wave them during the festival. As on every Jewish festival we also have special prayers, meals, and family and community events. Blessings.