Skeptics.SE is not a court of law. We can't decide on the guilt or innocence of a person - we can only report what courts have found.
The Pakistani Army court martialed Kulbhushan Jadhav, accepted a confession and sentenced him to death. [Press Release]
The Indian Government denied that he was a spy.
“The said individual has no link with the Government since his premature retirement from Indian Navy."
The International Court of Justice ruled that Pakistan had breached the Vienna convention by failing to give Jadhav consular access before the trial, and required that Pakistan review the conviction and sentence in light of this.