Hinduism is a religion that compromises of many schools of thought among which there are six prominent philosophical systems that try to assert the nature and reality of our existence.
The Prakruti and Purusha concept of our existence belongs to the Samkhya school of thought. As per Samkhya philosophy there is no God (a supreme ruling deity) who created the universe. The universe came into existence from primordial matter (Pradhana). Before the creation the three qualities Satva, Rajas and Tamas were in perfect equilibrium. But in course of time the symmetry broke and the universe came into existence. But pradhana or prakruti being inert, there exists another fundamental unit called purusha, which is responsible for all that is sentient in the universe. Hence, the world is an interaction between these two aspects.
So as per Samkhya Philosophy Prakruti and Purusha are the two fundamental units of our existence, but not deities who can be worshipped. So this can be stated as a dualistic philosophy not bi-theistic.
Now regarding Gita, it does talk about prakruti, the female counter part. Prakruti is shakti (energy), God is shaktimaan (reservoir or withholder of energy). So it is the sentient Shaktimaan who always controls the inert energy. Hence, controlling prakruti, God creates all the universes:
prakṛtiṁ svām avaṣṭabhya visṛjāmi punaḥ punaḥ [BG - 9.8]
- Subduing the prakruti under myself, I create the worlds again and again.
So the Samkhya Philosophy only asserts upto the two fundamental units of our existence. It doesn't accept the existence of God above it because there are no direct proofs. But if we go through other scriptures, then we will find that prakruti and purusha are nothing but two energy aspects of the Lord Himself. So God is the controller of the two:
eṣa vai bhagavān sākṣāt pradhāna-puruṣeśvaraḥ [SB - 7.15.27]
- God Himself is indeed the lord of pradhana (prakruti) and purusha
And the 13th chapter of Gita is completely devoted to the discussion of prakruti and purusha. So the core of Vedic philosophy is monotheistic (God or Paramatma is one without a second). But unlike other religions it accepts that the same God takes on many different forms and names as may be necessary. You may also want to read this answer on a similar topic.