Hi
I found a russian site how to root the Cube T8 Plus h**p://4pda.ru/forum/lofiversion/index.php?t695306.html. Here a short translation:
Disclaimer: ******* I'm not responsible for any damages *******
1. Download SuperSu directly to your Cube T8 from official site: h**p://download.chainfire.eu/supersu
2. Download Flash Utility/Driver on your PC: h**p://uploaded.net/file/eyo5yt8c
3. Download TWRP for Cube T8 on your PC: h**p://uploaded.net/file/o54jinin and extract its content to a folder.
Mirror: h**ps://drive.google.com/open?id=0B4UYz4J2xNyoaERDd3Zya01Ycmc
4. Install Device Driver from Step 2. on your PC (you have to agree Security warning). Depending on Windows version used, disabling Driver Signing might be required prior installation.
5. Start flash_tool.exe
6. Go to "Download" tab and Click "Scatter-Loading" Button, move to folder created in Step 3. and select the file "MT6753_Android_scatter.txt". Press the "Download" Button
7. Power down your Cube T8 tablet. After power down, connect it to a USB Port on your PC (No, you don't need to power it up - leave it powered down!). After a few moments, the flash tool should recognise the tablet and will install twrp recovery and should show "Success" Screen
8. Remove tablet from PC. Boot into Boot Selection by pressing Volume-Up and Power button simultaneously, Select "Recovery" and wait for twrp booting up.
9. In twrp, Install Zip File downloaded on Step 1. This should be found in Folder "MyFavorite"
10. Reboot device. By selecting "Reboot" in twrp, the device will hang. But don't worry; just press the power button for about 10 seconds for a forced reboot.
11. Voilà, you have a rooted Cube T8 Plus