Currently, I am trying to promote over 50+ fields in InfoPath so that I can publish them into SharePoint
How do I do it in much faster way? (Can it auto promote or other ways that can help me to increase the speed of promoting these fields?)
There is no faster way to do it, but:
If you want all of the fields on the form to correspond to a field in a list, then you should consider using a custom list and a custom infopath list form:
This is different from an InfoPath Form Library (which is the approach you show), in that every field corresponds to a field in the list. The main downside is that some field types and scenarios are not supported (ie repeating tables are not supported). If you do choose to use an InfoPath Form Library, then note you often don't need to promote every field. The rule of thumb I use is to only promote fields that I know users will want to search by or see in a list.