Can I export or convert a KiCad project to another EDA format (Altium, Mentor, Zuken, OrCAD etc.)?

No, KiCad doesn’t natively export to other formats for other EDA software packages, at least for the time being.

There are at least two practical reasons for that.

First, most commercial EDA file formats are closed, i.e. secret. It’s very difficult and time consuming to reverse engineer such a format. (This is a problem for all kinds of software, not just KiCad or EDA.)

Second, the development resources must be focused into areas which are the most important for KiCad project. The resources are limited, and it’s much more important to make KiCad a high quality EDA package than to export to other formats. It would offer little benefit for KiCad project, developers or users to try to write those converters which would require considerable effort.

A third reason isn’t maybe practical, it may be seen as a principle. (This isn’t in any way an official stance of the KiCad project nor does it necessarily represent a viewpoint of any of its developers). But think about this: you have already paid for your commercial software or will potentially be a paying customer. The software company wants you to use its product and to pay for it. Whose responsibility and benefit is it to offer conversion from KiCad to that other software? After all, KiCad has open (even human readable) file format, and that software company knows its own closed, proprietary format and has commercial interest. Maybe you should ask them.

(I would also like to add that for the same reason the helpful peer users in this forum aren’t at their best when offering you conversion services to help you to move away from KiCad to another, commercial software.)

That said, it may be possible to find some existing converter or a roundabout way to convert. KiCad file format is open by design and on purpose to ease collaboration and data exchange. Anyone who knows the other file format and has necessary skills and resources can write a converter; KiCad tries to make it as easy as possible even though it doesn’t offer such converter itself.