Essential can be followed by for or to, depending on what comes next. As 'establishing' is considered a noun, you can use either.
Before a noun or noun clause, for and to are both correct, as in these examples:
The river is essential for/to the region's economy.
Food is essential for/to life.
Using high quality materials is essential for/to achieving a good result.
Before a verb, use essential to, as in these examples:
It is essential to use the proper technique.
It's essential to arrive on time.