Duplicating one cell to another is simple. Set your source cell and your destination cell, and you're all good. Take note that referencing cells within one table is applicable for prefilled tables.
Use the formula to the destination cell,
=Source_cell
For example:
A1 - source cell (text field)
B1 - destination cell (formula field)
Use the formula to B1,
=A1
This is only applicable to copying from one cell to another in a single table. If you need to copy the information to another table, refer to the article "How to duplicate information from one cell to another cell in a another table (cross-referencing)".