Bhashya
सैषा चतुष्पदा षडक्षरपदा छन्दोरूपा सती भवति गायत्री षड्विधा—वाग्भूतपृथिवीशरीरहृदयप्राणरूपा सती षड्विधाभवति ।वाक्प्राणयोरन्यार्थनिर्दिष्टयोरपि गायत्रीप्रकारत्वम्,अन्यथा षड्विधसंख्यापूरणानुपपत्तेः ।तत् एतस्मिन्नर्थे एतत्गायत्र्याख्यं ब्रह्म गायत्र्यनुगतं गायत्रीमुखेनोक्तम् ऋचाअपि मन्त्रेणाभ्यनूक्तं प्रकाशितम् ॥
In plain words
This Gayatri, possessing four quarters and feet of six syllables, takes the form of a meter and becomes sixfold—manifesting as speech, the elements, the earth, the body, the heart, and the breath. Even when speech and breath are taught elsewhere for other purposes, they are still aspects of Gayatri; otherwise, the sixfold count could not be fulfilled. Therefore, in this sense, this Brahman known as Gayatri is spoken of through Gayatri and illuminated by the sacred verse.
Close to the Sanskrit
This four-footed, six-syllable-footed, meter-formed Gayatri becomes sixfold, being of the form of speech, elements, earth, body, heart, and breath. Speech and breath, even when designated for other purposes, are modes of Gayatri, otherwise the completion of the sixfold number would be impossible. That, in this meaning, this Brahman named Gayatri, followed by Gayatri, spoken through the mouth of Gayatri, is also recited and illuminated by the mantra.