first name is information that i ask for. in contact group i set this as text question. Can i restrict letters only. that is prohibit ability to type in numbers. e.g. john is accepted, john 111 is not accepted.
There is no built-in validation routine that will do this for you, so you will have to use the REGEX validation option. See the SurveyGizmo documentation for details – https://help.surveygizmo.com/help/textbox-answer-formats#regex-patterns-for-complex-validation.
The most commonly used Regex expressions are pre-loaded in SurveyGizmo. The documentation lists other useful Regex expressions, and there is one that will restrict entry to alpha characters only – ^[a-zA-Z0-9_]*$