Yes, TurboTax will automatically save your information you have already entered.
To Add a W-2,
follow the steps below.
1) Sign into TurboTax
Online
2) Continue your return by click Taxes > Tax Timeline > Take me to my return.
3) Click on the Federal Taxes tab
(Personal using Self-Employed w/ Business Tab)
4) Click on Wages and Income (Personal
Income using Self-Employed w/ Business Tab)
5) Click Jump to full list
6) On Wages
and Salaries, click Start/Revisit
7) On the W-2
Summary Screen click +Add a W-2.
For additional information,
please see the following FAQ article. https://ttlc.intuit.com/replies/4712124