آمين يا رب العالمين
Yes. Prior to Rasoolullaah صلى الله عليه وسلم becoming a Nabi, those who truly followed Nabi `Eesa عليه السلام and those who truly followed Nabi Moosaa عليه السلام were regarded as Muwahhidoon (Monotheists), and will go to Jannah, In Shaa Allaah.
Allaah Ta`aalaa says in the Qur'aan:
إِنَّ الَّذِينَ آمَنُوا وَالَّذِينَ هَادُوا وَالنَّصَارَى وَالصَّابِئِينَ مَنْ آمَنَ بِاللَّهِ وَالْيَوْمِ الْآخِرِ وَعَمِلَ صَالِحًا فَلَهُمْ أَجْرُهُمْ عِنْدَ رَبِّهِمْ وَلَا خَوْفٌ عَلَيْهِمْ وَلَا هُمْ يَحْزَنُونَ
{"Indeed, those who have Imaan, and those who were guided (i.e. the original Yahood), and the Nasaaraa, and the Saabi'een, those who believed in Allaah, in the Last Day, and did righteous deeds, they will receive their reward from their Rabb. There shall be no fear upon them and nor shall they grieve."} [Soorah al-Baqarah, 2:62]
This Aayah is in reference to those who truly followed their Ambiyaa, prior to the coming of Rasoolullaah Sallalaahu `Alayhi wa Sallam. As for after Rasoolullaah Sallallaahu `Alayhi wa Sallam was sent as a Nabi, then Allaah Ta`aalaa says:
وَمَنْ يَبْتَغِ غَيْرَ الْإِسْلَامِ دِينًا فَلَنْ يُقْبَلَ مِنْهُ وَهُوَ فِي الْآخِرَةِ مِنَ الْخَاسِرِينَ
{"Whosoever seeks a Deen other than Islaam, it will never ever be accepted from him, and he will be, in the Aakhirah (hereafter), from the Khaasireen (losers)."} [Soorah Aal-e-`Imraan, 3:85]
والسلام