One has to remember that Marx wrote his manifesto in the midst of the industrial revolution, when there was considerable abuse of monopoly power and definitely abuse of the working class in manual labor jobs. At that time, there were no laws regarding employment conditions, so the oligarchs were free to squeeze their people for all they could.
People working for a software firm are paid to generate intellectual property. A motivated, satisfied person is ten to twenty times as productive as an abused or disaffected person. Consequently, a Marx style industrial abusive work environment tends to destroy the company, as productivity plummets, and the most productive people leave for better working conditions.
The big difference between the industrial revolution and the tech revolution is - the tech revolution relies on inspiration and motivation, not pure sweat. Marx age working conditions are not only cruel, in the software field they are counterproductive.
Yes, there are 'software sweatshops'... anyone who works in software knows what companies to avoid. If you're good, you can find a position elsewhere.
So, to get back to your question - how would Marx categorize an entrepreneur? They don't really fit in to any of his categories, because both the economic and social conditions have changed so much since Marx's time.