What kind of position (importance) does Chaitanya Mahaprabhu enjoy in the sect called Gaudiya Vaishnavism?
To put it more precisely, can a person's opinions be considered as those of Gaudiya Vaishnavism if the opinions are found contradicting with what Chaitanya Mahaprabhu has said?
One of the main features that differentiates the Gaudiya Vaishnava Sect from the other vaishnava sects is accepting Sri Chaitanya alongwith Radha-Krishna as the Principal deity to be worshipped.In fact there are few temples of Gaudiya Vaishnavas where only idols of Mahaprabhu and Nityananda are worshipped. In fact it wont make much difference if instead of Gaudiya we use Gauriya as adjective of Vaishnava as Sri Chaitanya is also referred to as Sri Gaura or Sri Gaura-Hari.
The 'Gaudiya Vaishnava Darshan by Principal Radhagovinda Nath, D.Lit. reads
The path and tattvas advised by Mahaprabhu are the basis of the Gaudiya Vaishnava Darshana (vol 1 page 193).
The early biographies of Mahaprabhu that are held very highly by and are of the same glory as Srimad-Bhagavatam to the Gaudiya Vaishnavas are
1.Sri Chaitanya-Bhagavata by Vrindavan Das Thakur, who is considered as the Vyasa of Chaitanyalila.
Murari Gupta's Karcha
Chaitanya-Chandrodaya and Mahakavya by Kavi Karmnapur
Sri Sri Chaitanya-Charitamrita by Krishnadas Kaviraj.
All the above biographies describe Mahaprabhu as the Supreme Godhead Himself (ie not merely an incarnation) who appeared on earth to taste the sweetness of Radha-bhaava and to preach the yuga-dharma (Naama-Sankirtana).
There are the following subsects in the Gaudiya Vaishnavas:
The lineage of Prabhupaad Bijaykrishna Goswami , who was from the family of Advaita Acharya.
The different Goswamis who are from the family of Nityananda Mahaprabhu.
The lineage of Sripada Radha-Ramana Charanadas Babaji
The lineage of Sri Sri Jagadbandhusundara
5.The lineage of Sri Sri Baya Baba of Orissa
6.The lineage of Premananda Bharati
7.The lineage of Siddha Sri Jagannath Das Maharaj, Sri Chaitanya Das Maharaj, Sri Gaurkishore Das Maharaj etc
The lineage of Sri Kedarnath Dutta,Ex- Deputy Magistrate, whose disciples latter formed different Gaudiya Maths.
All of the above accept Mahaprabhu as God.So Mahaprabhu's sayings must be equivalent to 'Sri Bhagavan Ubacha' of Gita for all of them.So Mahaprabu's sayings have the highest importance.Also, the Vyasa of Mahaprabhu's leela is Vrindavan Das according to Sri Chaitanya-Charitamrita and so sayings and leelas of Mahaprabhu quoted in that book seems to be the most authentic. Almost all the temples established by the above-mentioned lineages compulsorily have idol or image of Mahapeabhu being worshipped with equal respect as Sri Radha-Krishna.
But how much of Mahaprabhu's teachings are actually followed is a different question altogether.
Hope this answers your question.
He is the founder of the sampradaya (tradition) and the leader of it, the chief acarya (teacher) in the tradition as well. A follower of the tradition should not contradict the tenets of the tradition taught by the leader and chief acarya. So if someone is contradicting Sri Caitanya's teaching, that cannot be an official Gaudiya Vaishnava opinion.
All that about Sri Caitanya is presented in the book Caitanya Caritamrta, his biography.
According to Chaitanya Charitamrita, he is believed to be an Avatara of Krishna:
He whom Śrīmad-Bhāgavatam describes as the son of Nanda Mahārāja has descended to earth as Lord Caitanya.
-CC Ādi 2.9:
Gaudiya Vaishnava tradition is one of several Vaishnava traditions (sampradayas), the devotees dedicated to the worship, devotional serving and surrender to Lord Vishnu, or more specifically Lord Krishna. All Vaishnava traditions are followers of the teaching of Vedanta, a system of philosophy primarily based on the Upanishads, Vedanta sutra (aka Brahma sutra) and Bhagavad-gita. Thus every Vaishnava tradition has its own system of Vedanta philosophy which is a distinguishing feature of that particular tradition making it differ from other Vaishnava traditions. The main distinguishing feature of the Gaudiya Vaishnava tradition is a system of Vedanta philosophy called Acintya bheda abheda tattva.
