This will be based on the following factors:
Your profile : Arun has been in finance and in the last 6 years worked for the biggest companies n smallest startups in Germany. In all of those roles, he was able to get through with English. This was an exception situation and should not be taken as a standard in Germany. Most of the finance profiles require fluent German language skills.
The reason for this is that as a finance professional, one needs to deal with the tax authorities, lawyers, legal authorities, state and federal authorities. All of this communication happens in German, so language is necessary.
Exceptions : mostly IT profiles. Due to high demand for IT professionals, language might not be most important criteria.
For all the other profiles : marketing, finance, HR, customer support, Ops, Logistics and supply chain - language will be required.
The company : The size and nature of the business your company is in will define the language requirements. It might be a big company, with operations only in the DACH region (D - Germany, A -Austria, CH - Switzerland). This means that all of their activities are in German, hence making language an important requirement.
The role : If you are really lucky, there might be small/big companies where you are catering to a function where English is the default language. For example : if you are a regulatory affairs professional in a Pharma company, then German may not be required. This roles implies that you are working with international authorities, so the language of communication will be English.
The clients/customers : Arun has a friend who works for a company making special cameras. These are mostly used in defense and corporations for security purposes across the globe. Now, if one is in sales and dealing with such customers/clients, then it implies that the language of communication will be English. It is very much possible though that the internal communication language can be German. Hence, while English might work externally, German will be required internally (to fulfill client orders and requests).
Having said all of the above, if you are planning to come to Germany for long term, it will be prudent to learn the language. Not only will it help in the professional world, it will make life a lot more easier and fun on the personal side.
It always helps to have a mentor, who has worked and lived in Germany for some of the best brands. For personal consultation with Arun Mahajan, book a time with him.