Is playing the lottery or Toto considered an ongoing sin (sayyi'ah jariyah), and does this sin cease with repentance and abstaining from it?

There is no concept in Islamic law called "continuous bad deed." However, whoever commits a sin and people follow his example bears the burden of his deed and the burden of those who followed him. "Whoever initiates a bad practice will bear its sin and the sin of whoever acts upon it thereafter." As for merely committing a sin like gambling, if the one who committed it does not guide others to it and repents with a sincere repentance, it is hoped that his repentance will be accepted and his sin erased, in confirmation of His (Allah's) saying, Exalted is He: "And whoever does evil or wrongs himself then seeks forgiveness of Allah will find Allah Forgiving and Merciful," and "Say, 'O My servants who have transgressed against themselves [by sinning], do not despair of the mercy of Allah. Indeed, Allah forgives all sins. Indeed, it is He who is the Forgiving, the Merciful.'"