Dear Hadi,
Dear Reader,
While we sincerely appreciate that you want to perform Hajj on your father's behalf, we cannot answer your question about whether that will allow him to enter heaven. Knowledge of that is beyond the reach of any human's perception. As evidenced by the Quran at 46:9 ("Say: I am no new thing among the messengers (of Allah), nor do I know what will be done with me or with you. I do but follow that which is inspired in me, and I am but a plain warner"), even Prophet Muhammad (pbuh) did not know what would happen to himself.
This is further emphasized by a well-known incident from the life of the Prophet (pbuh) surrounding the death of one of the companions Uthman bin Mazun who is reported to have been one of the most pious of the companions, and so devoted to worship, night prayers and fasting that the Prophet (pbuh) told him that he (the Prophet) had not been sent with a religion asking people to be ascetic monks.
When Uthman bin Mazun died, an Ansar woman (Umm al‑ʿĀlāʾ) who cared for him said: “May Allah have mercy on you ... I bear witness that Allah has certainly honoured you.”
That being said, you may be familiar with the hadith of the Prophet (pbuh) about the three things that can continue to benefit a person after their death: perpetual sadaqah (charity); knowledge by which benefit is acquired; a pious child who prays for the deceased (Sunan Abi Dawud). Given this, if you are able to pray for your father and/or perform a Hajj on his behalf, we encourage you to do so, and insha'Allah this will be accepted for both you and him.
In peace.