I am not sure whether the wording of your question is correct.
Overall knowledge of the hereafter is only with our Lord, and no one else. Allah swt decides whether we enter jannat or not, and He is The Most Fair to, so everyone will be judged accordingly.
It is obsolete chatter to otherwise speculate on whether this sin will stop access to jannat etc.
Allah says in quran
إِنَّ الصَّلَوةَ تَنْهَى عَنِ الْفَحْشَآءِ وَالْمُنْكَرِ
Verily, the Salah prevents from Al-Fahsha' (immoral sins) and Al-Munkar (evil deeds) [Al-Ankaboot 29:45]
Purpose of salah is to help us abstain from evil and indecency. When Allah makes it fard to pray, it does not mean that Allah is burdening us with mindless rituals. Na'uzubillah
It means that it is a mans need that he needs to pray 5 times a day in order to protect himself from evil and indecency and build that relationship with Allah.
From Ulema i have heard that namaz is what helps a man build his relationship with Allah. When we say takbir and fold our hands it is us and Allah, no third person in the middle.
With regards to going to heaven, that is Allahs judgement, i am not one to comment. As far as i am concerned we need to do our best. If you need help with getting the motivation to pray, khushu and khuzoo i suggest you look into tasawwuf.