What is the Gender of a company name?
What does it depend on?
Let's say Microsoft
for that matter.
Generally, proper names (like brand names) have no gender (and thus no article in front of them), but well-established brand names might adopt gender over time (Publicity agencies even recommend adding gender to your brand name as this creates the impression that it might be a well-established one).
There's the easy and the tricky cases - the easy ones are where the brand name is containing or alluding to a noun that has gender in German:
More tricky are acronyms - but still, if you expand them, you might be ending up with a definitive gender
Then there is another class for company and brand names that are no abbreviations. Often gender has been adopted over time, especially for brand names that are old and well-established, sometimes more than one gender is possible:
As you might see, we're slowly wandering away from safe grounds into non-rule territory - Here, the German language very often simply pulls back to my initial statement and assumes no gender at all, avoiding any possible problems. [example sentences taken from Wikipedia articles]
Microsoft as in your example is apparently one of those - You simply avoid any construct that assumes a specific gender:
Microsoft wurde am 4. April 1975 gegründet. Das Unternehmen [not: er, sie oder es!] hat etwa 148.000 Mitarbeiter und ist der größte Softwarehersteller der Welt.
If you absolutely want and need gender, then try and derive one from the company's legal denomination, in most cases you will be ending up with "Gesellschaft" (or "corporation"), thus ending up with female.
die Microsoft Corporation
The same is BTW true for some well-established German brands as well:
Die Daimler-Benz AG
But you will still encounter the "evade" strategy as above in follow-up sentences.
That is a more complex question than you might think. Duden has an elaborate page about it.
Not only the gender is relevant, but also the number (singular/plural).
Die Frankfurter Allgemeine Zeitung, Die Rügenwalder Mühle, ...
[Das Unternehmen] Microsoft hat hundert seiner Mitarbeiter entlassen / [Die Firma] Microsoft hat hundert ihrer Mitarbeiter entlassen
The words in the [brackets] can be obmitted.
Der Blumenhof OHG [...]
where OHG is short for offene Handelsgesellschaft
Die Blumenhof OHG, die Techno-Studios-Gesellschaft mbh sucht (singular!)
BMW hat seine Mitarbeiter entlassen / Die Bayrischen Motoren Werke stellen neue Mitarbeiter ein.
For most companies, we don't use an article at all, so they are kind of genderless.
Examples: "Microsoft hat ein neues Betriebssystem herausgebracht. Es gibt ein neues Betriebssystem von Microsoft" "Viele Leute warten schon mit großer Vorfreude auf das neue iPhone von Apple."
The products on the other hand have articles: "Hans fährt jetzt einen (der) Mercedes. Hans fährt jetzt einen Wagen von Mercedes Benz." "Mein Bruder hat sich ein (das) iPhone gekauft. Mein Bruder hat sich ein Handy von Apple gekauft."