Is there any limit for the number of control (text boxes) allowed on a form? I have a form with nearly 1000 text boxes and want to be sure InfoPath will allow this many. Thanks
If your form is a regular InfoPath template (not a SharePoint list form) you will only be limited in the amount of fields you can promote to a library (if the form is published to a SharePoint library) - to my knowledge, there is no constraint on the number of fields you can have in a form.
That said, a data source with 1,000 fields usually has potential for normalization - I often see data sources with lots of fields that should be using repeating structures instead - just a thought.
As far as I know the limit is based on the SharePoint Column limits that is 276 for Single line of text
You can check the details for the limits here