You need to know the difference between the two which you are talking about. "Digital Marketing" is a skill that can be acquired by experience but "Engineering" is a Profession, you can master it only if you got theoretical knowledge and exposure. If you got your family support and enough marks to proceed with your B.E/B.Tech in a reputed Engineering College then go ahead.
Digital Marketing is trending and everything in the world is Digital nowadays. It got a good scope but with my experience I could say anybody can learn Digital Marketing within a considerable amount of time. And one cannot rely on getting a job right after completing a certificate program in Digital Marketing. Digital Marketing has different components in it Search Engine Optimization, Search Engine Marketing , Social Media Marketing, Classified Listings,etc. It also involves certain level of writing and Designing skills. You can learn all this by following online lectures and tutorials easily and take up a job as a digital marketing associate anytime but getting an Engineering Degree can't be an easy task after crossing certain age.
Think and act accordingly as you are the only person who know your current family and financial positions.
All the Best.