The Windows installer (whether it be for Windows 8, Windows 7, or any other version) has the following properties that make it unlikely that it could run in Ubuntu:
- It is a Windows program, or, more accurately, a collection of Windows programs. (You can run some Windows programs on Ubuntu with Wine, but see below...).
- It uses Windows device drivers, and it cannot succeed without them. In almost all cases, Windows device drivers cannot be run on Ubuntu. Wine does not facilitate running Windows device drivers.
- It is written for a special build of Windows called the Windows Preinstallation Environment (sometimes written WinPE), which runs from a live CD/DVD or live USB flash drive. The installer is intended to run in exactly this way. Please note that this is a Windows live environment, which is different from an Ubuntu (or any other GNU/Linux) live environment. Even getting the Windows installer to run from an ordinary Windows system, or from a Windows live CD/DVD that is not based on the Windows Preinstallation Environment, would probably require substantial effort. Getting it to run on Ubuntu would require enormous effort (and luck).
Theoretically, if you have enough RAM, you could set up a virtual machine (for example, in VirtualBox or VMware Workstation) that uses your physical hard drive as its virtual hard drive. (Those virtualization solutions, and some others, support this.) You could use the virtual machine to run the Windows 8 installer. The problem with this is that the virtual machine would probably have markedly different hardware than your real machine.
With Ubuntu, you can take a system drive from one machine to another and usually it works with minimal hassle (unless you're taking a 64-bit installation over to a 32-bit machine).
But with Windows, that does not tend to work out of the box. If you did that, you likely would be unable to boot from your new system. You would probably have to do quite a bit of troubleshooting to get this to work.
I'm not saying it necessarily can't be done. But if your goal is to keep your programs, it's definitely more efficient to just reinstall them after performing a clean install of Windows 8. If you have installation media for whatever proprietary payware applications you have, it's definitely easier. And even if you don't, it's probably much easier to find them. If the applications you want to retain were present on your Windows 7 system when that system was installed, they may be on the custom Windows 7 installation disc that shipped with your computer. If your computer shipped with the applications installed on Windows 7 but with no installation disc, you may be able to restore the original state of the system (consult your manufacturer's documentation), or you may be able to order a DVD from your manufacturer at minimal expense, which would facilitate this action.
Please note that if you have documents and other important files (e.g., videos, ebooks, music) in your Windows 7 system, your Ubuntu live USB system can recover those. If you have trouble doing that, please feel free to post a new question about it!
If you want detailed information about how to install Windows 8 (using any of the techniques mentioned above, or any other way), that would be off-topic for Ask Ubuntu. I've tried to keep this answer essentially about Ubuntu. One good place to post questions about installing and using Windows is Super User.