Is it true that reciting the verses from Surat Al-Imran (Allah bears witness that there is no god but He...) up to (Say: O Allah, Master of the Kingdom...) fulfills seventy needs, the first of which is forgiveness?

The hadith mentioned in the question is weak and fabricated, and it is not permissible to act upon it. Nevertheless, reading the Quran generally contains immense good and virtue, and the Prophet commanded reading the Quran because it will intercede on the Day of Resurrection. He specifically mentioned the two luminous chapters (Al-Baqarah and Al 'Imran), stating that they will come on the Day of Resurrection like two clouds, arguing on behalf of their reciter. Furthermore, Allah's Greatest Name (Al-Ism Al-A'zham) is mentioned in two verses, one in Surat Al-Baqarah and the other in Surat Al 'Imran.